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Sample records for calamitic liquid crystalline

  1. Probing the Texture of the Calamitic Liquid Crystalline Dimer of 4-(4-Pentenyloxybenzoic Acid

    Directory of Open Access Journals (Sweden)

    Maher A. Qaddoura

    2010-01-01

    Full Text Available The liquid crystalline dimer of 4-(4-pentenyloxybenzoic acid, a member of the n-alkoxybenzoic acid homologous series, was synthesized using potassium carbonate supported on alumina as catalyst. The acid dimer complex exhibited three mesophases; identified as nematic, smectic X1 and smectic X2. Phase transition temperatures and the corresponding enthalpies were recorded using differential scanning calorimetry upon both heating and cooling. The mesophases were identified by detailed texture observations by variable temperature polarized light microscopy. The nematic phase was distinguished by a fluid Schlieren texture and defect points (four and two brushes while the smectic phases were distinguished by rigid marble and mosaic textures, respectively.

  2. Liquid crystalline polymers

    CERN Document Server

    Wang, Xin-Jiu

    2004-01-01

    This textbook consists of six chapters. The first chapter highlightsthe concept of liquid crystals, including chemical structure, phaseclassification, defect and texture, and continuum theory. It has beencarefully written to meet the needs of readers who do not specializein liquid crystals. The second chapter is related to the theoreticaldescription of liquid crystalline polymers, networks, and gels, whichdeals with subjects such as the formation of liquid crystallinity inthe polymer system, the phase transition and phase diagram, themolecular weight effect, chain conformation, physics proper

  3. Liquid crystalline dihydroazulene photoswitches

    DEFF Research Database (Denmark)

    Petersen, Anne Ugleholdt; Jevric, Martyn; Mandle, Richard J.; Davis, Edward J.; Cowling, Stephen J.; Goodby, John W.; Nielsen, Mogens Brøndsted

    2015-01-01

    DHA where the alignment is maintained. The systematic structural variation has revealed that a biaryl spacer between the DHA and the alkyl chain is needed for liquid crystallinity and that the one aromatic ring in the spacer cannot be substituted by a triazole. This work presents an important step...

  4. Liquid crystalline order in polymers

    CERN Document Server

    Blumstein, Alexandre

    1978-01-01

    Liquid Crystalline Order in Polymers examines the topic of liquid crystalline order in systems containing rigid synthetic macromolecular chains. Each chapter of the book provides a review of one important area of the field. Chapter 1 discusses scattering in polymer systems with liquid crystalline order. It also introduces the field of liquid crystals. Chapter 2 treats the origin of liquid crystalline order in macromolecules by describing the in-depth study of conformation of such macromolecules in their unassociated state. The chapters that follow describe successively the liquid crystalli

  5. Liquid Crystalline Microemulsions

    Science.gov (United States)

    Huang, Chien-Yueh; Petschek, Rolfe G.

    2000-03-01

    If an isotropic component of an emulsion is replaced by one having liquid crystalline (e.g. nematic) order the equilibrium behavior can change dramatically. There are long range enthalpic effects which can result in either repulsive or attractive interactions between the surfaces of an emulsion and entropic effects which generally result in an attractive interaction between these surfaces. We review briefly the possibility of stable blue-phase like microemulsions in mixtures of chiral nematics, appropriate surfactants and an incompatible isotropic solvent. We discuss the entropic effects in a lamellar phase, including the effects of changes in elastic constants and surface-nematic coupling. The effects of fluctuations on blue phases will be briefly discussed.

  6. Crystalline 'Genes' in Metallic Liquids

    CERN Document Server

    Sun, Yang; Ye, Zhuo; Fang, Xiaowei; Ding, Zejun; Wang, Cai-Zhuang; Mendelev, Mikhail I; Ott, Ryan T; Kramer, M J; Ho, Kai-Ming

    2014-01-01

    The underlying structural order that transcends the liquid, glass and crystalline states is identified using an efficient genetic algorithm (GA). GA identifies the most common energetically favorable packing motif in crystalline structures close to the alloy's Al-10 at.% Sm composition. These motifs are in turn compared to the observed packing motifs in the actual liquid structures using a cluster-alignment method which reveals the average topology. Conventional descriptions of the short-range order, such as Voronoi tessellation, are too rigid in their analysis of the configurational poly-types when describing the chemical and topological ordering during transition from undercooled metallic liquids to crystalline phases or glass. Our approach here brings new insight into describing mesoscopic order-disorder transitions in condensed matter physics.

  7. Unsymmetrical banana-shaped liquid crystalline compounds 1 derived from 2,7-dihydroxynaphtalene

    Directory of Open Access Journals (Sweden)

    Simion Aurel

    2015-01-01

    Full Text Available The synthesis and characterization of new bent-core asymmetric compounds derived from 2,7-dihydroxynaphtalene with various connecting groups between the aromatic rings and alkyloxy terminal substituents at the end of the long arm are presented. As calamitic promesogenic units some 1,4 - disubstituted phenylene rings with azo or ester linkage between them have been used. The synthetic strategies to obtain the final esteric derivatives involved the esterification of 7-(benzyloxynaphthalen-2-ol with 4-(4-alkyloxyphenylazobenzoyl chlorides or with 4-((4- (alkyloxybenzoyloxybenzoic acids in the presence of DCCI and DMAP. The mesomorphic properties have been assigned by optical polarizing microscopy and differential scanning calorimetry. All the compounds showed mesomorphic properties of enantiotropic or monotropic type, the liquid crystalline behavior depending on the linking group between the phenylene rings. Thermogravimetric studies evidenced that all compounds were stable in the range of the existence of mesophases.

  8. Liquid crystalline cellulose derivatives for mirrorless lasing

    OpenAIRE

    Wenzlik, Daniel

    2013-01-01

    In this thesis cholesteric films made of liquid crystalline cellulose derivatives with improved optical properties were prepared. The choice of the solvent, hydrogen bond influencing additives, the synthetic realization of a very high degree of substitution on the cellulosic polymer and the use of mechanical stirring at the upper concentration limit of the liquid crystalline range were the basis for an improved alignment of the applied cellulose tricarbamates. In combination with a tuned subs...

  9. Nanosecond liquid crystalline optical modulator

    Energy Technology Data Exchange (ETDEWEB)

    Borshch, Volodymyr; Shiyanovskii, Sergij V.; Lavrentovich, Oleg D.

    2016-07-26

    An optical modulator includes a liquid crystal cell containing liquid crystal material having liquid crystal molecules oriented along a quiescent director direction in the unbiased state, and a voltage source configured to apply an electric field to the liquid crystal material wherein the direction of the applied electric field does not cause the quiescent director direction to change. An optical source is arranged to transmit light through or reflect light off the liquid crystal cell with the light passing through the liquid crystal material at an angle effective to undergo phase retardation in response to the voltage source applying the electric field. The liquid crystal material may have negative dielectric anisotropy, and the voltage source configured to apply an electric field to the liquid crystal material whose electric field vector is transverse to the quiescent director direction. Alternatively, the liquid crystal material may have positive dielectric anisotropy and the voltage source configured to apply an electric field to the liquid crystal material whose electric field vector is parallel with the quiescent director direction.

  10. Mesogen-jacketed liquid crystalline polymers.

    Science.gov (United States)

    Chen, Xiao-Fang; Shen, Zhihao; Wan, Xin-Hua; Fan, Xing-He; Chen, Er-Qiang; Ma, Yuguo; Zhou, Qi-Feng

    2010-08-01

    This critical review covers the recent progress in the research of mesogen-jacketed liquid crystalline polymers (MJLCPs), special side-on side-chain liquid crystalline polymers with very short spacers or without spacers. MJLCPs can self-organize into supramolecular columnar phases with the polymer chains aligned parallel to one another or smectic phases with the backbones embedded in the smectic layers. The semi-rigid rod-like MJLCP with a tunable rod shape in both length and diameter provides an excellent building block in designing novel rod-coil liquid crystalline block copolymers which can self-assemble into hierarchical supramolecular nanostructures depending on the competition between liquid crystal formation and microphase separation (229 references). PMID:20559597

  11. Stability of liquid crystalline bridges

    Science.gov (United States)

    Mahajan, Milind P.; Tsige, Mesfin; Taylor, P. L.; Rosenblatt, Charles

    1999-02-01

    The stability of cylindrical bridges of the liquid crystal octylcyanobiphenyl in an immiscible liquid bath was investigated in the nematic and smectic A phases. In the nematic phase the bridge was found to destabilize at a length-to-diameter (slenderness) ratio R similar to that of ordinary Newtonian fluids. On the other hand, the Bingham behavior of the smectic A phase, i.e., an apparent yield stress, enabled the formation of stable columns with R well in excess of π.

  12. Thermotropic and lyotropic behaviour of new liquid-crystalline materials with different hydrophilic groups: synthesis and mesomorphic properties

    Directory of Open Access Journals (Sweden)

    Alexej Bubnov

    2013-02-01

    Full Text Available Several new calamitic liquid-crystalline (LC materials with flexible hydrophilic chains, namely either hydroxy groups or ethylene glycol units, or both types together, have been synthesized in order to look for new functional LC materials exhibiting both, thermotropic and lyotropic behaviour. Such materials are of high potential interest for challenging issues such as the self-organization of carbon nanotubes or various nanoparticles. Thermotropic mesomorphic properties have been studied by using polarizing optical microscopy, differential scanning calorimetry and X-ray scattering. Four of these nonchiral and chiral materials exhibit nematic and chiral nematic phases, respectively. For some molecular structures, smectic phases have also been detected. A contact sample of one of the prepared compounds with diethylene glycol clearly shows the lyotropic behaviour; namely a lamellar phase was observed. The relationship between the molecular structure and mesomorphic properties of these new LCs with hydrophilic chains is discussed.

  13. Carborane-containing liquid-crystalline polycrylates

    International Nuclear Information System (INIS)

    Carborane-containing homo- and copolyarylates were prepared by acceptor-catalytic polyesterification in solution from m-carboranedicarboxylic acid and 4,4'-dioxydiphenyl-o-carborane in combination with common dicarboxylic acids and bisphenols. The properties of the resulting polyarylates were studied, and the factors affecting the development of liquid-crystalline order in carborane-containing copolyarylates were discussed

  14. Liquid Crystalline Semiconductors Materials, properties and applications

    CERN Document Server

    Kelly, Stephen; O'Neill, Mary

    2013-01-01

    This is an exciting stage in the development of organic electronics. It is no longer an area of purely academic interest as increasingly real applications are being developed, some of which are beginning to come on-stream. Areas that have already been commercially developed or which are under intensive development include organic light emitting diodes (for flat panel displays and solid state lighting), organic photovoltaic cells, organic thin film transistors (for smart tags and flat panel displays) and sensors. Within the family of organic electronic materials, liquid crystals are relative newcomers. The first electronically conducting liquid crystals were reported in 1988 but already a substantial literature has developed. The advantage of liquid crystalline semiconductors is that they have the easy processability of amorphous and polymeric semiconductors but they usually have higher charge carrier mobilities. Their mobilities do not reach the levels seen in crystalline organics but they circumvent all of t...

  15. Dispersion of γ-Alumina Nano-Sized Spherical Particles in a Calamitic Liquid Crystal. Study and Optimization of the Confinement Effects

    Directory of Open Access Journals (Sweden)

    Sergio Diez-Berart

    2014-02-01

    Full Text Available We report an experimental study on confined systems formed by butyloxybenzylidene octylaniline liquid crystal (4O.8 + γ-alumina nanoparticles. The effects of the confinement in the thermal and dielectric properties of the liquid crystal under different densities of nanoparticles is analyzed by means of high resolution Modulated Differential Scanning Calorimetry (MDSC and broadband dielectric spectroscopy. First, a drastic depression of the N-I and SmA-N transition temperatures is observed with confinement, the more concentration of nanoparticles the deeper this depression is, driving the nematic range closer to the room temperature. An interesting experimental law is found for both transition temperatures. Second, the change in shape of the heat capacity peaks is quantified by means of the full width half maximum (FWHM. Third, the confinement does not noticeably affect the molecular dynamics. Finally, the combination of nanoparticles and the external applied electric field tends to favor the alignment of the molecules in metallic cells. All these results indicate that the confinement of liquid crystals by means of γ-alumina nanoparticles could be optimum for liquid crystal-based electrooptic devices.

  16. Synthesis of New Liquid Crystalline Diglycidyl Ethers

    OpenAIRE

    Issam Ahmed Mohammed; Rashidah Mohamed Hamidi

    2012-01-01

    The phenolic Schiff bases I–VI were synthesized by condensation reactions between various diamines, namely o-dianisidine, o-tolidine and ethylenediamine with vanillin or p-hydroxybenzaldehyde and subsequent reactions between these phenolic Schiff bases and epichlorohydrin to produce new diglycidyl ethers Ia–VIa. The structures of these compounds were confirmed by CHN, FT-IR, 1H-NMR, and 13C-NMR spectroscopy. Their thermotropic liquid crystalline behavior was studied using differential scannin...

  17. Liquid crystalline biopolymers: A new arena for liquid crystal research

    International Nuclear Information System (INIS)

    This paper gives a brief introduction to liquid crystals on the basis of biopolymers and reviews literature on liquid crystalline behaviour of biopolymers both in vitro and in vivo in relation to their implications in the fields of biology, medicine and material science. Knowledge in the field of biological liquid crystals is crucial for understanding complex phenomena at supramolecular level which will give information about processes involved in biological organization and function. The understanding of the interaction of theses crystals with electric, magnetic, optical and thermal fields will uncover mechanisms of near quantum-energy detection capabilities of biosystems

  18. Synthesis of New Liquid Crystalline Diglycidyl Ethers

    Directory of Open Access Journals (Sweden)

    Issam Ahmed Mohammed

    2012-01-01

    Full Text Available The phenolic Schiff bases I–VI were synthesized by condensation reactions between various diamines, namely o-dianisidine, o-tolidine and ethylenediamine with vanillin or p-hydroxybenzaldehyde and subsequent reactions between these phenolic Schiff bases and epichlorohydrin to produce new diglycidyl ethers Ia–VIa. The structures of these compounds were confirmed by CHN, FT-IR, 1H-NMR, and 13C-NMR spectroscopy. Their thermotropic liquid crystalline behavior was studied using differential scanning calorimetry (DSC and polarizing optical microscopy (POM. All the diglycidyl ethers prepared exhibit nematic mesophases, except for Va and VIa, which did not show any transition mesophases, but simply flow to liquids.

  19. Synthesis and properties of liquid crystalline polyurethanes

    Institute of Scientific and Technical Information of China (English)

    Xin Haobo; Zhang Yunfeng; Xing Zheng

    2006-01-01

    1,4-Bis(p-hydroxybenzoate)phenylene was prepared using 1,4-bis(trimethylsiloxy)benzene and p-hydroxybenzoyl chloride as starting materials.A series of novel 1,4-bis(p-hydroxyalkoxybenzoate)phenylene were synthesized by reaction of 1,4-bis(p-hydroxybenzoate)phenylene with 3-bromopropanol and 4-bromobutanol,respectively,The liquid crystal polyurethanes were prepared by 1,4-bis(p-hydroxyalkoxybenzoate)phenylene with MDI (p-methylene diphenylenediisocyanate) and 2,4-TDI(2,4-toluenediisocyanate),respectively.The thermotropic properties,the melting point (Tm) and the isotropization temperature (Ti) of the synthesized polyurethanes were characterized by DSC,IR and POM.It showed that all of the polyurethane polymers exhibited thermotropic liquid crystalline properties between 144℃ and 260℃.The transition temperature (Tm and Ti) decreased with an increase in the length of the methylene spacer.

  20. Controlling the Morphology of Side Chain Liquid Crystalline Block Copolymer Thin Films through Variations in Liquid Crystalline Content

    OpenAIRE

    Verploegen, Eric; Zhang, Tejia; Jung, Yeon Sik; Ross, Caroline; Hammond, Paula T.

    2008-01-01

    In this paper we describe methods for manipulating the morphology of side-chain liquid crystalline block copolymers through variations in the liquid crystalline content. By systematically controlling the covalent attachment of side chain liquid crystals to a block copolymer (BCP) backbone, the morphology of both the liquid crystalline (LC) mesophase and the phase segregated BCP microstructures can be precisely manipulated. Increases in LC functionalization lead to stronger preferences for the...

  1. Liquid crystalline elastomers as stimuli-responsive microactuators

    OpenAIRE

    Fleischmann, Eva-Kristina

    2013-01-01

    Liquid crystalline elastomers (LCEs) are known to perform a reversible change of shape upon the phase transition from the semi-ordered liquid crystalline state to the chaotic isotropic state. This unique behavior of these “artificial muscles” arises from the self-organizing properties of liquid crystals (mesogens) in combination with the entropy-elasticity of the slightly crosslinked elastomer network. In this work, micrometer-sized LCE actuators are fabricated in a microfluidic setup. The mi...

  2. Novel ion-containing liquid crystals and liquid crystalline polymers

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, P.

    1992-01-01

    The properties of main chain polymeric liquid crystals (PLC's) based on trans-1,2-bis(4,4[prime]-pyridyl)ethylene mesogens, alkyl spacers and various counterions are described. The mesomorphic properties of model compounds are also described. Some of these are based on [open quotes]Siamese twin[close quotes] systems with the 4-alkoxystilbazole mesogen similar to the trans-1,2-bis(4,4[prime]-pyridyl)ethylene used in the polymer. Some model compounds are low molecular mass monomer analogues of the polymer. The structural parameters investigated were the length of the flexible spacer, the nature of the mesogen, the ionic density of the system and the nature and size of the counterion. The introduction of ionic sites into a main chain PLC's far from inhibiting appears to promote mesophase formation and enhance the stability of the mesophase. The phenomena described here involve high transition temperatures strong odd-even oscillations and supercooling effects. The twins and polymers display a great variety of smectic mesophases, the nature of which depends strongly on the nature of the counterion. Large organic counterions such as methylsulfonates promote the formation of smectic mesophases, sometimes of lower order (S[sub A] or S[sub C]) whilst toluenesulfonate promote often higher order smectic polymorphism. The polymers display also lyotropic liquid crystallinity.

  3. Liquid crystalline phases in concentrated aqueous solutions of Na+ DNA.

    OpenAIRE

    Rill, R L

    1986-01-01

    Concentrated aqueous saline solutions of short (146-base-pair) DNA fragments suddenly become turbid and iridescent when the DNA concentration is slightly increased or the temperature is decreased. Microscopic examination through crossed polarizing filters shows that turbidity and iridescence is due to formation of a liquid crystalline DNA phase similar to cholesteric liquid crystals formed by other semirigid, but nonelectrolyte, chiral polymers. Several distinct textures of the liquid crystal...

  4. Liquid crystallinity driven highly aligned large graphene oxide composites

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyung Eun; Oh, Jung Jae; Yun, Taeyeong [Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 305-701 (Korea, Republic of); Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701 (Korea, Republic of); Kim, Sang Ouk, E-mail: sangouk.kim@kaist.ac.kr [Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 305-701 (Korea, Republic of); Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701 (Korea, Republic of)

    2015-04-15

    Graphene is an emerging graphitic carbon materials, consisting of sp{sup 2} hybridized two dimensinal honeycomb structure. It has been widely studied to incorporate graphene with polymer to utilize unique property of graphene and reinforce electrical, mechanical and thermal property of polymer. In composite materials, orientation control of graphene significantly influences the property of composite. Until now, a few method has been developed for orientation control of graphene within polymer matrix. Here, we demonstrate facile fabrication of high aligned large graphene oxide (LGO) composites in polydimethylsiloxane (PDMS) matrix exploiting liquid crystallinity. Liquid crystalline aqueous dispersion of LGO is parallel oriented within flat confinement geometry. Freeze-drying of the aligned LGO dispersion and subsequent infiltration with PDMS produce highly aligned LGO/PDMS composites. Owing to the large shape anisotropy of LGO, liquid crystalline alignment occurred at low concentration of 2 mg/ml in aqueous dispersion, which leads to the 0.2 wt% LGO loaded composites. - Graphical abstract: Liquid crystalline LGO aqueous dispersions are spontaneous parallel aligned between geometric confinement for highly aligned LGO/polymer composite fabrication. - Highlights: • A simple fabrication method for highly aligned LGO/PDMS composites is proposed. • LGO aqueous dispersion shows nematic liquid crystalline phase at 0.8 mg/ml. • In nematic phase, LGO flakes are highly aligned by geometric confinement. • Infiltration of PDMS into freeze-dried LGO allows highly aligned LGO/PDMS composites.

  5. Liquid crystallinity driven highly aligned large graphene oxide composites

    International Nuclear Information System (INIS)

    Graphene is an emerging graphitic carbon materials, consisting of sp2 hybridized two dimensinal honeycomb structure. It has been widely studied to incorporate graphene with polymer to utilize unique property of graphene and reinforce electrical, mechanical and thermal property of polymer. In composite materials, orientation control of graphene significantly influences the property of composite. Until now, a few method has been developed for orientation control of graphene within polymer matrix. Here, we demonstrate facile fabrication of high aligned large graphene oxide (LGO) composites in polydimethylsiloxane (PDMS) matrix exploiting liquid crystallinity. Liquid crystalline aqueous dispersion of LGO is parallel oriented within flat confinement geometry. Freeze-drying of the aligned LGO dispersion and subsequent infiltration with PDMS produce highly aligned LGO/PDMS composites. Owing to the large shape anisotropy of LGO, liquid crystalline alignment occurred at low concentration of 2 mg/ml in aqueous dispersion, which leads to the 0.2 wt% LGO loaded composites. - Graphical abstract: Liquid crystalline LGO aqueous dispersions are spontaneous parallel aligned between geometric confinement for highly aligned LGO/polymer composite fabrication. - Highlights: • A simple fabrication method for highly aligned LGO/PDMS composites is proposed. • LGO aqueous dispersion shows nematic liquid crystalline phase at 0.8 mg/ml. • In nematic phase, LGO flakes are highly aligned by geometric confinement. • Infiltration of PDMS into freeze-dried LGO allows highly aligned LGO/PDMS composites

  6. LYOTROPIC LIQUID CRYSTALLINE BEHAVIOR OF FIVE CHITOSAN DERIVATIVES

    Institute of Scientific and Technical Information of China (English)

    Yan-ming Dong; Zhi-qiang Li

    1999-01-01

    Five chitosan derivatives, i.e. O-butyryl chitosan, O-benzoyl chitosan, N-phthaloyl chitosan, N-maleoyl chitosan and O-cyanoethyl chitosan, were prepared from chitosan. All of them had better solubilitythan chitosan, and demonstrated lyotropic liquid crystalline behavior in various solvents. The critical liquid crystalline behavior of three O-substituted chitosan derivatives was evidently different from two Nsubstituted analogues. Typical fingerprint textures of cholesteric phase were only observed in three Osubstituted derivatives. The critical concentration (v/v%) of three O-substituted derivatives does not depend on the acidity of acidic solvents.

  7. Photochromic liquid crystalline structures containing azobenzene moieties

    Czech Academy of Sciences Publication Activity Database

    Studenovský, Martin; Sedláková, Zdeňka; Wang, Geng; Nešpůrek, Stanislav; Janus, K.; Boiko, O. P.; Kajzar, F.

    2004-01-01

    Roč. 212, č. 1 (2004), s. 399-406. ISSN 1022-1360. [Electrical and Related Properties of Polymers and Other Organic Solids /9./. Prague, 14.07.2002-18.07.2002] R&D Projects: GA MŠk OC D14.30 Institutional research plan: CEZ:AV0Z4050913 Keywords : azobenzene * liquid crystal * photochromism Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.691, year: 2004

  8. In-situ photopolymerization of oriented liquid-crystalline acrylates

    OpenAIRE

    Broer, Dirk Jan

    1990-01-01

    The scope of this thesis concerns a new method to produce oriented polymers by the in-situ photopolymerization of oriented liquid-crystalline acrylates. The desired macroscopic molecular order is already accomplished in the monomeric state prior to the polymerization. ... Zie: Summary

  9. Characterization of quasi-liquid crystalline spiroxazine derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jin-Ho; Kim, Sung-Hoon; Kim, Jae-Ho

    2004-01-05

    The structures of new spiroxazine derivatives containing a megogenic group attached to 9-position of the naphthoxazine ring was synthesized and characterized by their photo- and thermochromic properties and the intrinsic liquid crystal behavior. All of these derivatives showed the reversible photo- and thermochromism near the melting temperature and only one derivative demonstrated quasi-liquid crystalline behavior. The structural changes as increasing the sample temperature were monitored by FT-IR. The photochromic response of visible absorption at 575 and 606 nm upon 365-nm irradiation was also monitored by UV-Vis absorption spectroscopy. DSC data showed that compound 1 demonstrated a phase transition at near 65 deg. C during cooling and heating cycle followed by the iso-melting process. Furthermore, polarizing microscopic study and X-ray diffraction (XRD) measurement indicated that compound 1 demonstrated Schlieren texture and nematic liquid crystalline characteristics with one-directional isotropic alignment.

  10. LIQUID CRYSTALLINE BEHAVIOR OF AROMATIC COPOLYAMIDE IN CONCENTRATED SULPHURIC ACID

    Institute of Scientific and Technical Information of China (English)

    SHAN Guorong; PAN Zhicun; LIU Deshan; ZHOU Qixiang

    1997-01-01

    The liquid crystalline behavior of anisotropic solutions in 100% sulphuric acid of aromatic copolyamide obtained by low-temperature solution copolycondensation of terephthalic acid chloride (TPC), p-phenylene diamine (PPD) and 4, 4'-diamino-diphenylether (DAPE) has been studied by optical microscopy and X-ray diffraction. The effects of inherent viscosity, concentration of copolyamide in sulphuric acid, the content of the third monomer (DAPE) and sequence distribution of copolyamide on the critical concentration,isotropic temperature, phase diagram and texture of liquid crystal were investigated.The schlieren texture was observed and the results of X-ray diffraction indicate that the concentrated solutions of copolyamide exhibit nematic liquid crystalline behavior.

  11. Synthesis of azobenzene-containing liquid crystalline gelator for use in liquid crystal gels

    Institute of Scientific and Technical Information of China (English)

    Guang Wang; Xiao Liang Zhao; Yue Zhao

    2008-01-01

    A liquid crystalline gelator containing the azobenzene chromophore was synthesized for the first time; it was used to form self-assembled network in nematic liquid crystals resulting in liquid crystal gels with distinct features.? 2008 Guang Wang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

  12. Molecular reorientations in a substance with liquid-crystalline and plastic-crystalline phases

    International Nuclear Information System (INIS)

    Results of dielectric relaxation (DR), quasielastic neutron scattering (QNS), far infrared absorption (FIR), proton magnetic resonance (PMR), differential scanning calorimetry (DSC) and preliminary X-ray diffraction measurements on the di-n-pentyloxyazoxybenzene (5.OAOB) are presented. The measurements carried out by all these methods showed that 5.OAOB exhibits a nontypical for liquid-crystalline materials phase diagram. It has two mesophases: a nematic (N) and an ''intermediate'' crystalline phase just below it. A complex interpretation of results obtained is given. All suggestions concerning the character of reorientational motions of the molecule as a whole as well as of its segments in mesomorphic phases are analyzed. From comparison of the DR and QNS studies one can conclude that in the N phase the molecule as a whole performs rotational diffusion around the long axis (τDR ∼ 100 ps) and at the same time the two moieties perform faster independent reorientations around N - benzene rings bonds withτQNS ∼ 5 ps. On the basis of various experimental data it is shown that the CrI phase is a plastic-crystalline phase for which the molecule and its segments perform fast stochastic unaxial reorientations. This is the first case where the existence of such a phase in liquid-crystalline materials has been experimentally confirmed. (author)

  13. Liquid Crystalline Network Composites Reinforced by Silica Nanoparticles

    Directory of Open Access Journals (Sweden)

    Zhen Li

    2014-07-01

    Full Text Available Liquid crystalline networks (LCNs are a class of polymers, which are able to produce mechanical actuation in response to external stimuli. Recent creation of LCNs with exchangeable links (xLCNs makes LCNs easy moldable. As the xLCNs need to be shaped at a high temperature, it is important to enhance their thermal and mechanical properties. In this paper, a series of xLCNs/SiO2 composites containing 1%–7% SiO2 nanoparitcles (SNP were prepared and their thermal and mechanical properties were examined. The results show that xLCNs/SNP composites have lower liquid crystalline-isotropic phase transition temperature and higher decomposition temperature than pure LCN. The tensile strength and the elongation at break of xLCNs at high temperatures were also enhanced due to the addition of SNPs.

  14. Synthesis and characterization of thermotropic liquid crystalline polyimides

    Indian Academy of Sciences (India)

    Sachin Mane; C R Rajan; Surendra Ponrathnam; Nayaku Chavan

    2015-10-01

    Non-symmetrical and linear dyad-based mesogens were synthesised containing imine or ester bridging group. In the present work, due to the absence of branching in diamine-based mesogen, the structure has—rigidity inversely imine/ester bridging groups between two benzene rings imparts—flexible property to the mesogen and consequently rigid–flexible property has been balanced. The synthesised mesogens were characterized by different techniques including nuclear magnetic resonance and Fourier transform infrared spectroscopy. Liquid crystalline polymers (LCPs) were synthesised using pyromellitic dianhydride and 4-[(4-aminobenzylidene)amino]aniline or 4-aminophenyl-4-aminobenzoate. Subsequently, thermotropic liquid crystalline polymers (TLCPs) have also been evaluated to obtain optical microscopy textures at different temperatures which demonstrated interesting and notable changes. It is worth noting that marble-like textures were observed upto 200 ° C.

  15. PROPERTIES AND MICROSTRUCTURE OF AROMATIC LIQUID CRYSTALLINE COPOLYESTERS

    Institute of Scientific and Technical Information of China (English)

    WANG Yong; WU Dacheng; LI Ruixia

    1997-01-01

    The properties and structures of thermotropical liquid crystalline copolyesters based on p-hydroxybenzoic acid (PHBA), terephthalic acid (TPA) and biaphenol A (BPA) were studied by DSC, WAXD, hot stage polarized microscopy and NMR. It was found that most of the copolyesters were soluble in many common organic solvents. The copolyesters had low Tm/Tf values and a broad range of liquid crystal phase, making the polymers readily melt-processable. The effects of annealing at different temperatures on the copolyester containing 33% PHBA were also discussed. It was noted that annealing at ca. 200℃ (below Tc - n) could lead to the increasing of the crystallinity of the copolyester while the microstructure and sequence structure had not changed. Annealing at ca. 280℃ (near Tc - n) could bring a change of crystal and sequence structure and simultaneously made the microdomains be ordered more perfectly.

  16. Supramolecular routes towards liquid crystalline side-chain polymers

    OpenAIRE

    Hammond, Matthew R.; Mezzenga, Raffaele

    2008-01-01

    Supramolecular attachment of mesogenic or non-mesogenic side chains to polymer backbones can result in the formation of liquid crystalline morphologies. The various parameters that can be tuned in order to achieve these morphologies, such as the type of non-covalent bonding chemistry (hydrogen bonding, ionic bonding, metal coordination, π–π interactions), the polymeric template architecture, and the side chain structure and properties, are reviewed in what follows, with emphasis placed on the...

  17. Side-chain liquid crystalline polyesters for optical information storage

    DEFF Research Database (Denmark)

    Ramanujam, P.S.; Holme, Christian; Hvilsted, Søren;

    1996-01-01

    Azobenzene side-chain liquid crystalline polyester structures suitable for permanent optical storage are described. The synthesis and characterization of the polyesters together with differential scanning calorimetry and X-ray investigations are discussed. Optical anisotropic investigations and...... holographic storage in one particular polyester are described in detail and polarized Fourier transform infrared spectroscopic data complementing the optical data are presented. Optical and atomic force microscope investigations point to a laser-induced aggregation as responsible for permanent optical storage....

  18. Perhydroazulene-based liquid-crystalline materials with smectic phases

    OpenAIRE

    Zakir Hussain; Henning Hopf; S. Holger Eichhorn

    2012-01-01

    New liquid-crystalline materials with a perhydroazulene core were synthesized and the stereochemistry of these compounds was investigated. The mesomorphic properties of the new LC compounds were investigated by differential scanning colorimetry, polarizing optical microscopy and X-ray diffraction. We report here on the LC properties of nonchiral materials, which predominantly exhibit smectic phases and display nematic phases only within narrow temperature ranges. The dependence of the mesogen...

  19. Selection of Thermotropic Liquid Crystalline Polymers for Rotational Molding

    OpenAIRE

    Scribben, Eric Christopher

    2004-01-01

    Thermotropic liquid crystalline polymers (TLCPs) possess a number of physical and mechanical properties such as: excellent chemical resistance, low permeability, low coefficient of thermal expansion, high tensile strength and modulus, and good impact resistance, which make them desirable for use in the storage of cryogenic fluids. Rotational molding was selected as the processing method for these containers because it is convenient for manufacturing large storage vessels from thermoplastics....

  20. Experimental Results on Electrorheology of Liquid Crystalline Polymer Solutions

    Science.gov (United States)

    Neves, S.; Leal, C. R.; Cidade, M. T.

    2008-07-01

    The electrorheological (ER) effect is known as the enhancement of the apparent viscosity upon application of an external electric field. Suspensions of polarizable particles in non-conducting solvents are the most studied electrorheological fluids, however, liquid crystalline materials may also present ER effect as long as their dielectric anisotropy is positive. In the liquid crystalline state of a positive dielectric anisotropy, the application of the electric field makes the director align perpendicular to the flow direction, thus increasing the apparent viscosity. In this work results of two liquid crystalline polymer solutions, acetoxypropylcellulose (APC) in dimethylacetamide (DMAc) and poly-γ-benzyl-L-glutamate (PBLG) in 1,4-dioxane, presenting opposite behavior upon application of the electric field, will be presented. APC/DMAc (negative dielectric anisotropy) presents a decrease of the apparent viscosity upon application of the electric field, as expected, while PBLG/1,4-dioxane (positive dielectric anisotropy) presents the opposite behavior. For this last solution we will present the shear flow curves for different electric fields in function of polymer molecular weight and solution concentration.

  1. Computational analysis of ordering in non-liquid crystalline versus liquid crystalline materials with special reference to nBAC

    International Nuclear Information System (INIS)

    A computational analysis of ordering in non-liquid crystalline p-n-alkyl benzoic acid, having 1 (1BAC), 2 (2BAC) and 3(3BAC) carbon atoms in the alkyl chain has been carried out with respect to translatory and orientational motions, but detailed results are reported only for 3BAC. The evaluation of net atomic charges and dipole moments at each atomic center has been carried out using complete neglect differential overlap (CNDO/2) method. The modified Rayleigh-Schrodinger perturbation theory along with the multicentered-multipole expansion method has been employed to evaluate long-range interactions, while a '6-exp' potential function has been assumed for short-range interactions. On the basis of stacking, in-plane and terminal interaction energy calculations, all possible arrangements of a molecular pair have been considered. A comparative picture of molecular parameters, such as total energy, binding energy, and total dipole moment of 3BAC with higher homologous series liquid crystalline compounds having 4(4BAC), 5(5BAC), and 6(6BAC) alkyl chain carbon atoms, has been given. It is found that, if a suitable functional group is attached to 3BAC, so that the length to breadth ratio is increased, the molecule will show a change in the long-range order, the phase transition temperature and other liquid crystalline properties.

  2. Dry Powder Precursors of Cubic Liquid Crystalline Nanoparticles (cubosomes)

    International Nuclear Information System (INIS)

    Cubosomes are dispersed nanostructured particles of cubic phase liquid crystal that have stimulated significant research interest because of their potential for application in controlled-release and drug delivery. Despite the interest, cubosomes can be difficult to fabricate and stabilize with current methods. Most of the current work is limited to liquid phase processes involving high shear dispersion of bulk cubic liquid crystalline material into sub-micron particles, limiting application flexibility. In this work, two types of dry powder cubosome precursors are produced by spray-drying: (1) starch-encapsulated monoolein is produced by spray-drying a dispersion of cubic liquid crystalline particles in an aqueous starch solution and (2) dextran-encapsulated monoolein is produced by spray-drying an emulsion formed by the ethanol-dextran-monoolein-water system. The encapsulants are used to decrease powder cohesion during drying and to act as a soluble colloidal stabilizer upon hydration of the powders. Both powders are shown to form (on average) 0.6 μm colloidally-stable cubosomes upon addition to water. However, the starch powders have a broader particle size distribution than the dextran powders because of the relative ease of spraying emulsions versus dispersions. The developed processes enable the production of nanostructured cubosomes by end-users rather than just specialized researchers and allow tailoring of the surface state of the cubosomes for broader application

  3. Transport of Liquid Phase Organic Solutes in Liquid Crystalline Membranes

    OpenAIRE

    Han, Sangil

    2010-01-01

    Porous cellulose nitrate membranes were impregnated with 8CB and PCH5 LCs (liquid crystals) and separations of solutes dissolved in aqueous phases were performed while monitoring solute concentration via UV-VIS spectrometry. The diffusing organic solutes, which consist of one aromatic ring and various functional groups, were selected to exclude molecular size effects on the diffusion and sorption. We studied the effects on solute transport of solute intra-molecular hydrogen bonding and so...

  4. Quantitative Analysis of Matrine in Liquid Crystalline Nanoparticles by HPLC

    Directory of Open Access Journals (Sweden)

    Xinsheng Peng

    2014-01-01

    Full Text Available A reversed-phase high-performance liquid chromatographic method has been developed to quantitatively determine matrine in liquid crystal nanoparticles. The chromatographic method is carried out using an isocratic system. The mobile phase was composed of methanol-PBS(pH6.8-triethylamine (50 : 50 : 0.1% with a flow rate of 1 mL/min with SPD-20A UV/vis detector and the detection wavelength was at 220 nm. The linearity of matrine is in the range of 1.6 to 200.0 μg/mL. The regression equation is y=10706x-2959 (R2=1.0. The average recovery is 101.7%; RSD=2.22%  (n=9. This method provides a simple and accurate strategy to determine matrine in liquid crystalline nanoparticle.

  5. Properties of ER Fluids Comprised of Liquid Crystalline Polymers

    Science.gov (United States)

    Inoue, Akio; Ide, Yoichiroh; Maniwa, Shyunji; Yamada, Hiroyuki; Oda, Hiroji

    Side-chain liquid crystalline polysiloxanes (LCS) diluted with solvents show a large increase in viscosity and a newtonian flow under an electric field. Two types of solvent-diluted LCSs, A and B, are presented and their properties are described in this paper. Type A shows a large temperature-dependent ER effect a quick response of msec. order to an electric field and a dynamic behavior similar to that of a low molecular weight liquid crystal. Type B shows a stable ER effect throughout a wide range of temperatures up to 150°C, a two-step response of shear stress curve upon application of DC electric field and a micron-sized droplets structure which deforms with the electric field. The generation mechanisms of ER effect on the two types were discussed with the data of dynamic and morphological changes, referring those on a low molecular liquid crystal and a particle dispersion type ER fluid.

  6. Polymer and Polymer Gel of Liquid Crystalline Semiconductors

    Institute of Scientific and Technical Information of China (English)

    Teppei Shimakawa; Naoki Yoshimoto; Jun-ichi Hanna

    2004-01-01

    It prepared a polymer and polymer gel of a liquid crystalline (LC) semiconductor having a 2-phenylnaphthalene moiety and studied their charge carrier transport properties by the time-of-flight technique. It is found that polyacrylate having the mesogenic core moiety of 2-phenylnaphtalene (PNP-acrylate) exhibited a comparable mobility of 10-4cm2/Vs in smectic A phase to those in smectic A (SmA) phase of small molecular liquid crystals with the same core moiety, e.g., 6-(4'-octylphenyl)- 2-dodecyloxynaphthalene (8-PNP-O12), and an enhanced mobility up to 10-3cm2/Vs in the LC-glassy phase at room temperature, when mixed with a small amount of 8-PNP-O12. On the other hand, the polymer gel consisting of 20 wt %-hexamethylenediacrylate (HDA)-based cross-linked polymer and 8-PNP-O12 exhibited no degraded mobility when cross-linked at the mesophase. These results indicate that the polymer and polymer composite of liquid crystalline semiconductors provide us with an easy way to realize a quality organic semiconductor thin film for the immediate device applications.

  7. 21 CFR 524.2620 - Liquid crystalline trypsin, Peru balsam, castor oil.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Liquid crystalline trypsin, Peru balsam, castor... NEW ANIMAL DRUGS § 524.2620 Liquid crystalline trypsin, Peru balsam, castor oil. (a)(1) Specifications... delivered to the wound site contains 0.12 milligram of crystalline trypsin, 87.0 milligrams of Peru...

  8. Intestinal mucus and juice glycoproteins have a liquid crystalline structure

    International Nuclear Information System (INIS)

    X-ray diffraction patterns have been obtained from the following components of canine gastrointestinal tract: (1) native small intestine mucus layer; (2) the precipitate of the flocks formed in the duodenal juice with decreasing pH; (3) concentrated solutions of glycoproteins isolated from the duodenal juice. The X-ray patterns consist of a large number of sharp reflections of spacings between about 100 and 4 A. Some reflections are common for all components studied. All the patterns are interpreted as arising from the glycoprotein molecules ordered into a liquid crystalline structure. (author)

  9. Intestinal mucus and juice glycoproteins have a liquid crystalline structure

    Energy Technology Data Exchange (ETDEWEB)

    Denisova, E.A.; Lazarev, P.I.; Vazina, A.A.; Zheleznaya, L.A.

    1985-11-05

    X-ray diffraction patterns have been obtained from the following components of canine gastrointestinal tract: (1) native small intestine mucus layer; (2) the precipitate of the flocks formed in the duodenal juice with decreasing pH; (3) concentrated solutions of glycoproteins isolated from the duodenal juice. The X-ray patterns consist of a large number of sharp reflections of spacings between about 100 and 4 A. Some reflections are common for all components studied. All the patterns are interpreted as arising from the glycoprotein molecules ordered into a liquid crystalline structure.

  10. THERMOTROPIC LIQUID CRYSTALLINE COPOLYESTERS-SOLID STATE POLYMORPHISM

    Institute of Scientific and Technical Information of China (English)

    XIE ping; LU Daohui; BAO Jingsheng

    1988-01-01

    This paper offers some new evidence on the polymorphism of solid state of liquid crystalline aromatic copolyesters which were prepared in our laboratory. The effects of different treatment conditions(quenching and annealing) on solid structure have been examined mainly by DSC and X-ray diffraction. The discussion focuses on the supercooled mesophase and low temperature solid-solid transition, the shifting of double melting peaks of annealed samples and the changing of their △H data depending on the treatment temperature, time and thermal scanning rate.

  11. New composites based on liquid crystalline elastomers and electroactive nanomaterials

    Czech Academy of Sciences Publication Activity Database

    Domenici, V.; Župančič, B.; Remškar, M.; Laguta, Valentyn; Veracini, C.A.; Zalar, B.

    Zurich : Trans Tech Publications Ltd, 2009 - (Vincenzini, P.; BarCohen, Y.; Carpi, F.), s. 34-39 ISBN 978-3-908158-27-1. ISSN 1662-0356. - (Advances in Science and Technology. 61). [3rd International Conference on Smart Materials, Structures and Systems. Acireale (IT), 08.06.2008-13.06.2008] Grant ostatní: Marie Curie Action-EC(XE) 039643 Institutional research plan: CEZ:AV0Z10100521 Keywords : liquid crystalline elastomers * nanoparticles * nanowires Subject RIV: BM - Solid Matter Physics ; Magnetism

  12. ELECTROCHROMETIC STUDIES ON POLAR MULTILAYERS OF LIQUID CRYSTALLINE POLYMERS

    Institute of Scientific and Technical Information of China (English)

    GONG Mingxuan; REN Yanzhi; LIU Wang; GAO Manglai; ZHAO Yingying; BAI Yubai; LI Tiejin

    1995-01-01

    Electrochrometic measurements were carried on the Z-type Langmuir-Blodgett films oftwo liquid crystalline polymers: mono- {6-[4-(phenylazo) naphthyloxy] hexyl } (1a) andmono- { 6-[4- (anthraquinone-1-azo) naphthyloxy] hexyl} (2a) ester of polymaleic acid . Itwas found that for both polymers, poling fields parallel and antiparallel to dipole momentsof the polymer side chains induce red and blue shift in absorption bands, respectively. Forpolymer la blue shift is accompanied by absorbance increase, while red shift by absorbancedecrease;but for polymer 2a only decrease in absorbance is observed. A simple model wasproposed to analyze the results.

  13. A Molecular View of Liquid Crystalline Elastomers and Gels

    Science.gov (United States)

    de Pablo, Juan

    2011-03-01

    A combination of Monte Carlo and molecular dynamics simulations is used to examine the order-disorder transitions that arise in model liquid crystalline elastomers and colloidal gels as a function of concentration and strain, respectively. Two models are considered. In the first, a lattice model is used to represent a colloidal gel of nematogens and nanoparticles. In the second, a cross-linked elastomer of Gay-Berne mesogens is adopted to examine the order-disroder transition that arises as a function of strain. The results of simulations are compared to those of recent experiments for these two classes of systems.

  14. New theories for smectic and nematic liquid crystalline polymers

    International Nuclear Information System (INIS)

    A summary of results from new statistical-physics theories for both backbone and side-chain liquid crystalline polymers (LCPs) and for mixtures with LCPs is presented. Thermodynamic and molecular ordering properties (including odd-even effects) have been calculated as a function of pressure, density, temperature, and molecule chemical structures (including degree of polymerization and the following properties of the chemical structures of the repeat units: lengths and shapes, intra-chain rotation energies, dipole moments, site-site polarizabilities and Lennard-Jones potentials, etc.) in nematic and multiple smectic-A LC phases and in the isotropic liquid phase. These theories can also be applied to combined LCPs. Since these theories have no ad hoc or arbitrarily adjustable parameters, these theories have been used to design new LCPs and new solvents and to predict and explain properties

  15. Volume phase transitions of cholesteric liquid crystalline gels

    Energy Technology Data Exchange (ETDEWEB)

    Matsuyama, Akihiko, E-mail: matuyama@bio.kyutech.ac.jp [Department of Bioscience and Bioinformatics, Faculty of Computer Science and Systems Engineering, Kyushu Institute of Technology, Kawazu 680-4, Iizuka, Fukuoka 820-8502 (Japan)

    2015-05-07

    We present a mean field theory to describe anisotropic deformations of a cholesteric elastomer without solvent molecules and a cholesteric liquid crystalline gel immersed in isotropic solvents at a thermal equilibrium state. Based on the neoclassical rubber theory of nematic elastomers, we derive an elastic energy and a twist distortion energy, which are important to determine the shape of a cholesteric elastomer (or gel). We demonstrate that when the elastic energy dominates in the free energy, the cholesteric elastomer causes a spontaneous compression in the pitch axis and elongates along the director on the plane perpendicular to the pitch axis. Our theory can qualitatively describe the experimental results of a cholesteric elastomer. We also predict the first-order volume phase transitions and anisotropic deformations of a gel at the cholesteric-isotropic phase transition temperature. Depending on a chirality of a gel, we find a prolate or oblate shape of cholesteric gels.

  16. Dynamic-Mechanical Analysis of Monodomain Nematic Liquid Crystalline Elastomers

    Science.gov (United States)

    Hotta, Atsushi; Terentjev, Eugene

    2003-03-01

    Dynamic-mechanical analysis was performed in the glassy, nematic and isotropic states of several monodomain nematic liquid crystalline elastomers (LCE) which differ in their degrees of anisotropy and internal microstructure. It was found that the type of network crosslinker makes a significant difference in the equilibrium properties of these elastomers, in particular, in their effective anisotropy. In spite of these differences, the observed dynamic-mechanical behaviour was very similar. The fact that there is a consistently high and wide loss over the whole nematic region, where storage modulus G' behaves non-monotonically, is most likely an indicator of the fact that the dynamic-mechanical response is not linear. Master curves have been built between the glassy state and the nematic-isotropic phase transition, where the modulus reaches a low-level soft plateau. Above the nematic-isotropic transition temperature Tni, the modulus rises substantially, since internal relaxation is no longer able to reduce the elastic response - and further time-temperature superposition fails. The dynamics of these elastomers are dominated by power laws, which was confirmed by the successful procedure of the master curve inversion (time-frequency inversion) to describe the static stress relaxation. Interestingly, it was found that mechanical properties characterized by power laws (in time) of stress relaxation match very well with the dynamic properties, where power laws (in frequency) were also observed in the dynamic modulus in the appropriate range of temperatures. The work demonstrates the potential for the use of nematic liquid crystalline elastomers in many acoustic and vibration damping applications.

  17. STUDY ON THE BLENDS OF NYLON 66 AND LIQUID CRYSTALLINE POLYESTERS

    Institute of Scientific and Technical Information of China (English)

    Zhang Shufan; Ren Jinghong

    1991-01-01

    Blends of polyamide (Nylon 66 ) with two different kinds of liquid crystalline polyesters were studied in all the composition range. Homogeneous samples were obtained by coprecipitation from 2wt%. solution of blends. The thermal properties, crystallinity and morphology of these blends were studied by using DSC, polarizing microscopy, and scanning electron microscopy. The phase transition and morphology of the blends are markedlyinfluenced by the composition of liquid crystalline polyesters. The mechanical behaviour of PHB/HNA-Nylon 66 blend was improved .although polyamide (Nylon 66)with the liquid crystalline polyesters were incompatible, but a rather strong interaction between the polymers did exist.

  18. Broadening of mesophase temperature range induced by doping calamitic mesogen with banana-shaped mesogen

    Science.gov (United States)

    Cvetinov, Miroslav; Stojanović, Maja; Obadović, Dušanka; Vajda, Aniko; Fodor-Csorba, Katalin; Eber, Nandor

    2016-03-01

    We have investigated three binary mixtures composed of selected banana-shaped dopant in low concentrations and calamitic mesogen in high. Banana-shaped dopant forms a B7 phase, while the calamitic mesogen exhibit nematic and smectic SmA and SmC phases. The occurring mesophases have been identified by their optical textures. At dopant concentrations of 2.2 and 3.1 mol%, there is evident broadening of nematic and smectic SmA temperature ranges in respect to the pure calamitic compound. Yet, the mixture with dopant concentration of 7 mol% exhibits narrower temperature ranges of mesophases. Increasing dopant concentration caused lowering of all phase transitions temperatures (TI-N, TN-SmA, TSmA-SmC) in all investigated mixtures. Therefore, mixing classic calamitic compounds with novel banana-shaped compound in low concentrations is viable way to attain useful mesophase range for application in industry.

  19. Thin liquid-crystalline polymer films : nucleation, crystallisation, instabilities and growth

    OpenAIRE

    Wielen, van der, AM Jeroen

    1999-01-01

    Liquid-crystalline polymers, LCPs, possess an ordered liquid state between their crystalline solid state and their isotropic state. It is not only their ordering that makes this material interesting but actually their hybrid character, i.e., they behave both like liquid crystals and like polymers. In the bulk this class of material has been studied extensively and it is still under further study. However, studies of the surface phenomena and thin films of LCPs are very scarce.What started as ...

  20. A least squares closure approximation for liquid crystalline polymers

    Science.gov (United States)

    Sievenpiper, Traci Ann

    2011-12-01

    An introduction to existing closure schemes for the Doi-Hess kinetic theory of liquid crystalline polymers is provided. A new closure scheme is devised based on a least squares fit of a linear combination of the Doi, Tsuji-Rey, Hinch-Leal I, and Hinch-Leal II closure schemes. The orientation tensor and rate-of-strain tensor are fit separately using data generated from the kinetic solution of the Smoluchowski equation. The known behavior of the kinetic solution and existing closure schemes at equilibrium is compared with that of the new closure scheme. The performance of the proposed closure scheme in simple shear flow for a variety of shear rates and nematic polymer concentrations is examined, along with that of the four selected existing closure schemes. The flow phase diagram for the proposed closure scheme under the conditions of shear flow is constructed and compared with that of the kinetic solution. The study of the closure scheme is extended to the simulation of nematic polymers in plane Couette cells. The results are compared with existing kinetic simulations for a Landau-deGennes mesoscopic model with the application of a parameterized closure approximation. The proposed closure scheme is shown to produce a reasonable approximation to the kinetic results in the case of simple shear flow and plane Couette flow.

  1. In situ deuteron NMR investigations of sheared liquid crystalline polymers.

    Science.gov (United States)

    Siebert, Hartmut; Becker, Patrick; Quijada-Garrido, Isabel; Grabowski, David A; Schmidt, Claudia

    2002-01-01

    The flow behavior of nematic liquid crystalline polysiloxanes of the side-chain type is studied by in situ 2H NMR spectroscopy on samples under shear in a cone-and-plate cell. The director orientation as a function of applied shear rate is determined from the quadrupole splitting of the spectra. The data analysis yields the two Leslie viscosity coefficients alpha2 and alpha3 and the flow-alignment parameter lambda = -(alpha3 + alpha2)/(alpha3 - alpha2). The values of lambda were determined for several homopolymers with only one type of side chain and random copolymers containing two different side chains. The results show that the flow behavior is related to the phase structure of the polymers, which varies with their composition. Only polymers with large amounts of smectic clusters in the nematic state show the tumbling instability (absolute value(lambda) polymers are flow aligning (absolute value(lambda) > or = 1). For some polymers, a transition from tumbling at low temperature to flow aligning at high temperatures was observed. PMID:12469817

  2. Oriented Liquid Crystalline Polymer Semiconductor Films with Large Ordered Domains.

    Science.gov (United States)

    Xue, Xiao; Chandler, George; Zhang, Xinran; Kline, R Joseph; Fei, Zhuping; Heeney, Martin; Diemer, Peter J; Jurchescu, Oana D; O'Connor, Brendan T

    2015-12-01

    Large strains are applied to liquid crystalline poly(2,5-bis(3-tetradecylthiophen-2yl)thieno(3,2-b)thiophene) (pBTTT) films when held at elevated temperatures resulting in in-plane polymer alignment. We find that the polymer backbone aligns significantly in the direction of strain, and that the films maintain large quasi-domains similar to that found in spun-cast films on hydrophobic surfaces, highlighted by dark-field transmission electron microscopy imaging. The highly strained films also have nanoscale holes consistent with dewetting. Charge transport in the films is then characterized in a transistor configuration, where the field effect mobility is shown to increase in the direction of polymer backbone alignment, and decrease in the transverse direction. The highest saturated field-effect mobility was found to be 1.67 cm(2) V(-1) s(-1), representing one of the highest reported mobilities for this material system. The morphology of the oriented films demonstrated here contrast significantly with previous demonstrations of oriented pBTTT films that form a ribbon-like morphology, opening up opportunities to explore how differences in molecular packing features of oriented films impact charge transport. Results highlight the role of grain boundaries, differences in charge transport along the polymer backbone and π-stacking direction, and structural features that impact the field dependence of charge transport. PMID:26552721

  3. MORPHOLOGICAL STUDIES OF A THERMOTROPIC SIDE-CHAIN LIQUID CRYSTALLINE POLYMER DURING MESOPHASE TRANSITIONS

    Institute of Scientific and Technical Information of China (English)

    Chi-bing Tan; Quan-ling Zhang; Shu-fan Zhang; Xia-yu Wang; Mao Xu

    1999-01-01

    The morphological features of a side-chain liquid crystalline polymer during the mesophase transitions were investigated by using the DSC technique. The polymer used was polyacrylate with mesogens of three benzene rings attached to the main chain through a flexible spacer. A special two-phase texture was observed in the transition temperature range. Similar to main-chain liquid crystalline polymers the transition process of the side-chain liquid crystalline polymer was composed of an initiation of the new phase at local places of the old phase matrix and a growth process of the new phase domains.

  4. Multiscale modeling of liquid crystalline/nanotube composites

    Science.gov (United States)

    Patrale, Sharil

    The objective of this research is to synthesize structural composites designed with particular areas defined with custom modulus, strength and toughness values in order to improve the overall mechanical behavior of the composite. Such composites are defined and referred to as 3D-designer composites. These composites will be formed from liquid crystalline polymers and carbon nanotubes. The fabrication process is a variation of rapid prototyping process, which is a layered, additive-manufacturing approach. Composites formed using this process can be custom designed by apt modeling methods for superior performance in advanced applications. The focus of this research is on enhancement of Young's modulus in order to make the final composite stiffer. Strength and toughness of the final composite with respect to various applications is also discussed. We have taken into consideration the mechanical properties of final composite at different fiber volume content as well as at different orientations and lengths of the fibers. The orientation of the LC monomers is supposed to be carried out using electric or magnetic fields. A computer program is modeled incorporating the Mori-Tanaka modeling scheme to generate the stiffness matrix of the final composite. The final properties are then deduced from the stiffness matrix using composite micromechanics. Eshelby's tensor, required to calculate the stiffness tensor using Mori-Tanaka method, is calculated using a numerical scheme that determines the components of the Eshelby's tensor (Gavazzi and Lagoudas 1990). The numerical integration is solved using Gaussian Quadrature scheme and is worked out using MATLAB as well. MATLAB provides a good deal of commands and algorithms that can be used efficiently to elaborate the continuum of the formula to its extents. Graphs are plotted using different combinations of results and parameters involved in finding these results.

  5. Physics of liquid and crystalline plasmas: Future perspectives

    Science.gov (United States)

    Morfill, G. E.

    It has been shown that under certain conditions "complex plasmas" (plasma containing ions, electrons and charged microspheres) may undergo spontaneous phase changes to become liquid and crystalline, without recombination of the charge components. Hence these systems may be regarded as new plasma states "condensed plasmas". The ordering forces are mainly electrostatic, but dipolar effects, anisotropic pressure due shielding, ion flow focussing etc. may all play a role, too. Complex plasmas are of great interest from a fundamental research point of view because the individual particles of one plasma component (the charged microspheres) can be visualised and hence the plasma can be studied at the kinetic level. Also, the relevant time scales (e.g. 1/plasma frequency) are of order 0.1 sec, the plasma processes occur practically in "slow motion". We will discuss some physical processes (e.g. wave propagation, shocks, phase transitions) of these systems and outline the potential of the research for the understanding of strongly coupled systems. Technologically, it is expected that colloidal plasmas will also become very important, because both plasma technology and colloid technology are widely developed already. In this overview first the basic forces between the particles are discussed, then the phase transitions, the lattice structures and results from active experiments will be presented. Finally the future perspectives will be discussed, from the scientific potential point of view and the experimental approaches in the laboratory and in space. Experiments under microgravity conditions are of great importance, because the microspheres are 10's of billions times heavier than the ions.

  6. Optical and topographic changes in water-responsive patterned cholesteric liquid crystalline polymer coatings

    Science.gov (United States)

    Stumpel, Jelle E.; Broer, Dirk J.; Bastiaansen, Cees W. M.; Schenning, Albert P. H. J.

    2014-05-01

    In this work, we present patterned water-responsive coatings, which alter both their topological and optical properties. The polymer coatings are based on a hydrogen-bonded cholesteric liquid crystalline polymer network. A two-step photopolymerization procedure leads to a patterned coating with repeating liquid crystalline and isotropic areas. The cholesteric liquid crystalline areas reflect green light, whilst the isotropic areas are transparent for visible light. Treatment with alkaline solution results in a hygroscopic polymer salt coating. When placed in demineralized water, the polymer films swells, leading to an enhancement of the surface topography structure in which the liquid crystalline areas swell more. Moreover, the pitch of the helical organization in the cholesteric areas increases due to this swelling leading to a color change from green to red.

  7. Selection of thermotropic liquid crystalline polymers for rotational molding

    Science.gov (United States)

    Scribben, Eric

    Thermotropic liquid crystalline polymers (TLCPs) possess a number of physical and mechanical properties such as: excellent chemical resistance, low permeability, low coefficient of thermal expansion, high tensile strength and modulus, and good impact resistance, which make them desirable for use in the storage of cryogenic fluids. Rotational molding was selected as the processing method for these containers because it is convenient for manufacturing large storage vessels from thermoplastics. Unfortunately, there are no reports of successful TLCP rotational molding in the technical literature. The only related work reported involved the static coalescence of two TLCP powders, where three key results were reported that were expected to present problems that preclude the rotational molding process. The first result was that conventional grinding methods produced powders that were composed of high aspect ratio particles. Secondly, coalescence was observed to be either slow or incomplete and speculated that the observed difficulties with coalescence may be due to large values of the shear viscosity at low deformation rates. Finally, complete densification was not observed for the high aspect ratio particles. However, the nature of these problems were not evaluated to determine if they did, in fact, create processing difficulties for rotational molding or if it was possible to develop solutions to the problems to achieve successful rotational molding. This work is concerned with developing a resin selection method to identify viable TLCP candidates and establish processing conditions for successful rotational molding. This was accomplished by individually investigating each of the phenomenological steps of rotational molding to determine the requirements for acceptable performance in, or successful completion of, each step. The fundamental steps were: the characteristics and behavior of the powder in solids flow, the coalescence behavior of isolated particles, and the

  8. Cure reaction and phase behavior of liquid crystalline epoxides-anhydride systems

    Institute of Scientific and Technical Information of China (English)

    Li Yan Liang; Shao Ping Ren; Yi Quan Zheng; Man Geng Lu

    2007-01-01

    A series of novel liquid crystalline epoxides with lateral substituents were cured with anhydrides and the cure kinetics was investigated by non-isothermal DSC technique. The results showed that the lengths of lateral substituents have great effect on the value of Ea. The curing reaction became less active, when the liquid crystalline epoxides have long lateral substituents and were controlled by diffusion at the late stage of cure. A nematic structure was observed by POM and XRD.

  9. REFRACTOMETRY AND TEXTURES OF METHYL-CYANOETHYL CELLULOSE/DICHLOROACETIC ACID LIQUID CRYSTALLINE SOLUTIONS

    Institute of Scientific and Technical Information of China (English)

    HUANG Yong; WU Bingkun

    1992-01-01

    An Abbe' refractometer with a rotatable polarizer mounted on the eyepiece is used for determining the two principal refractive indices of methyl-cyanoethyl cellulose/dichloroacetic acid liquid crystalline solutions. The critical concentration where the mesophase appears can be determined according to the variation of the increment of the refractive index with the concentration. Mesophase textures of the liquid crystalline solutions are observed and the influence of the concentration on mesophase textures is also discussed.

  10. A NEW STRATEGY FOR THE DESIGN OF LIQUID CRYSTALLINE POLYMERS WITH FLEXIBLE AND APOLAR BUILDING BLOCKS

    Institute of Scientific and Technical Information of China (English)

    K.C. Gupta; H.K. Abdulkadir; S. Chand

    2003-01-01

    The synthesis and characterization of a new series of liquid crystalline polymers, poly(dicycloalkyl vinylterephthalate)s, are reported. The basic building blocks of these polymers are not mesogenic by themselves. However,very stable mesophases can be generated by self-assembly of the polymer molecules. This approach suggests a novel design strategy of liquid crystalline polymers with flexible and apolar building blocks.

  11. Effect of heat and film thickness on a photoinduced phase transition in azobenzene liquid crystalline polyesters

    DEFF Research Database (Denmark)

    Sanchez, C; Alcala, R; Hvilsted, Søren;

    2003-01-01

    The liquid crystal to isotropic phase transition induced with 488 nm light in films of liquid crystalline azobenzene polyesters has been studied as a function of temperature, light intensity, and film thickness. That phase transition is associated with the photoinduced trans-cis-trans isomerizati......The liquid crystal to isotropic phase transition induced with 488 nm light in films of liquid crystalline azobenzene polyesters has been studied as a function of temperature, light intensity, and film thickness. That phase transition is associated with the photoinduced trans...

  12. Charge carrier transport in liquid crystals

    International Nuclear Information System (INIS)

    The materials exhibiting charge carrier mobility ranging from 10−3 to 0.1 cm2/Vs, i.e., between those of amorphous and crystalline materials, had been missing before the 1990s when the electronic conduction in liquid crystals was discovered. Since then, various liquid crystalline materials including discotic and calamitic liquid crystals have been studied in order to clarify their charge carrier transport properties in liquid crystalline mesophases. In this article, the historical background of the discovery of electronic conduction in liquid crystals, intrinsic and extrinsic conductions, unique properties of the charge carrier transport, the effect of molecular alignment on it, and the conduction mechanism in liquid crystalline mesophases are shortly described on the basis of the experimental and theoretical studies accumulated in these two decades, noting that the missing materials were liquid crystals. - Highlights: • Liquid crystals exhibit charge mobility ranging from 10–3 to 0.1 cm2/Vs. • Electronic (intrinsic) and ionic (extrinsic) conductions in liquid crystals • Unique charge carrier transport properties in liquid crystals • Effect of molecular alignment in mesophases on charge carrier transport • Conduction mechanism in smectic liquid crystals

  13. Cross-Linked Liquid Crystalline Systems From Rigid Polymer Networks to Elastomers

    CERN Document Server

    Broer, Dirk

    2011-01-01

    With rapidly expanding interest in liquid crystalline polymers and elastomers among the liquid crystal community, researchers are currently exploring the wide range of possible application areas for these unique materials, including optical elements on displays, tunable lasers, strain gauges, micro-structures, and artificial muscles. Written by respected scientists from academia and industry around the world, who are not only active in the field but also well-known in more traditional areas of research, "Cross-Linked Liquid Crystalline Systems: From Rigid Polymer Networks to Elastomers&qu

  14. SYNTHESIS AND PROPERTIES OF NEW MESOGEN-JACKETED LIQUID CRYSTALLINE POLYMERS

    Institute of Scientific and Technical Information of China (English)

    Qi-ding Mi; Qi-feng Zhou

    2000-01-01

    Some new mesogen-jacketed liquid crystalline polymers (MJLCP) with polymer backbones, spacers, and mesogenic units of different structures were synthesized by radical polymerization. The mesomorphic behavior of these polymers was examined using differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). Their liquid crystallinity is influenced by the variation of polymer backbone, spacer, mesogenic unit and its terminal groups. The results show that 1) a more flexible polymer main-chain is more favorable to the formation of a liquid crystal phase, while 2)a flexible spacer will decrease the "Jacket Effect" and the liquid crystallinity and 3) a subtle modification of the terminal groups on the mesogenic unit may also have a significant influence on properties of the polymers.

  15. Orientation of liquid crystalline materials by using carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Kamanina N.V.

    2011-01-01

    Full Text Available The solution of some problems, where the initial black field is necessary for the regime of light transmission through the electrooptical organic nematic liquid crystal structures has been considered via a homeotropic alignment of liquid crystal molecules on the substrate covered by carbon nanotubes. The results of this investigation can be used to develop optical elements for displays with vertical orientations of nematic liquid crystal molecules (for example, for MVA-display technology.

  16. Photoluminescence of porous silicon with liquid crystalline fillers

    International Nuclear Information System (INIS)

    Luminescence spectra of both pure porous silicon and filled with liquid crystals 5CB and H109 which emit radiation in violet spectral region are investigated. It is shown that there are bands of both porous silicon and a liquid crystal in the luminescence spectrum of porous silicon with liquid crystall filler. Thus the intensity of the band corresponding to porous silicon increases several times in comparison with a luminescence of pure porous silicon without filler. Experimental results are explained by internal no radiating swapping of energy from a liquid crystal to porous silicon

  17. THERMAL ANALYSIS AND STRUCTURE STUDIES ON THE BLENDS OF LIQUID CRYSTALLINE COPOLYESTERS AND PET, PBT

    Institute of Scientific and Technical Information of China (English)

    XIE Ping; LU Daohui

    1987-01-01

    The apparent uniform blends of liquid crystalline aromatic copolyesters and semiflexible polyesters PET or PBT were obtained by mechanical mixing in the molten state within certain range of composition.The effects of blending with liquid crystalline components on the structure of homopolyester matrix were examined by thermal analysis and X-ray diffraction. These results suggest that the LC component in the blend may possibly be acting as a nucleating agent, or it may induce axial orientation of molecules promoting the local ordering of matrix. For the blends of PET, these influences mainly display in narrowing the width of cold crystalline peak and enhancing the main peak of x-ray diffraction; and for the blends of PBT, the pre-melting crystalline peak was enhanced.

  18. Dislocation Model for Restacking Phase Transitions in Crystalline-B Liquid Crystals

    OpenAIRE

    Hirth, J. P.; Pershan, Peter S.; Collett, J; Sirota, E.; Sorensen, L. B.

    1984-01-01

    A dislocation-mediated model is presented for restacking phase transitions that have been observed in a variety of lamellar (liquid crystalline) systems. The model explains the existence of nonhexagonal crystalline (smectic)-B phases in terms of dislocation-induced tilting of hexagonally packed layers. Ordered dislocation arrays explain both the symmetry and the amplitude of observed modulations. It is likely that the model will also be applicable to modulated lipid-water phases.

  19. SYNTHESIS AND PROPERTIES OF NEW SIDE-CHAIN LIQUID CRYSTALLINE POLYMER WITH LATERALLY ATTACHED MESOGENS BY ESTER GROUP

    Institute of Scientific and Technical Information of China (English)

    Qi-ding Mi; Qi-feng Zhou

    1999-01-01

    New liquid crystalline monomer, 2,5-bis[(4'-methoxyphenoxy)carbonyl]phenyl acrylate was successfully synthesized. Polyacrylate with laterally attached mesogens via ester linkage was also derived.This polymer forms an enantiotropic liquid crystal phase while its monomer exhibits a metastable nematic phase with respect to the crystalline state. However, its liquid crystallinity is very low as compared to that of poly { 2,5-bis[(4'-methoxyphenoxy)carbonyl] -styrene }.

  20. Crystalline Surface Phases of the Liquid Au-Si Eutectic Alloy

    OpenAIRE

    Shpyrko, Oleg G.; Streitel, Reinhard; Balagurusamy, Venkatachalapathy S. K.; Grigoriev, Alexei Yu.; Deutsch, Moshe; Ocko, Benjamin M.; Meron, Mati; Lin, Binhua; Pershan, Peter S.

    2007-01-01

    A two dimensional crystalline layer is found at the surface of the liquid eutectic Au$_{82}$Si$_{18}$ alloy above its melting point $T_M=359 ^{\\circ}$C. Underlying this crystalline layer we find a layered structure, 6-7 atomic layers thick. This surface layer undergoes a first-order solid-solid phase transition occurring at $371 ^{\\circ}$C. The crystalline phase observed for T$>$371 $^{\\circ}$C is stable up to at least 430 $^{\\circ}$C. Grazing Incidence X-ray Diffraction data at T$>$371 $^{\\c...

  1. (Meth)acrylate liquid crystalline polymers for membrane applications

    Czech Academy of Sciences Publication Activity Database

    Rabie, F.; Sedláková, Zdeňka; Sheth, S.; Marand, E.; Martin, S. M.; Poláková, Lenka

    2015-01-01

    Roč. 132, č. 43 (2015), 42694_1-42694_8. ISSN 0021-8995 Institutional support: RVO:61389013 Keywords : copolymers * liquid crystals * membranes Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.768, year: 2014

  2. Enhanced light absorption in graphene via a liquid-crystalline optical diode

    Science.gov (United States)

    Pantazi, Aikaterini Iria; Yannopapas, Vassilios

    2016-09-01

    We demonstrate theoretically that light absorption in graphene can be boosted via a light-trapping mechanism based on a liquid-crystalline optical diode. The optical diode consists of twisted-nematic and nematic liquid-crystalline slabs. In particular, we show that, using a proper optical-diode setup, the absorption in a single graphene layer can be enhanced by a factor of four. By varying the pitch of the twisted-nematic liquid-crystalline slabs comprising the diode, one can tune the operating spectral region of the diode and thus enhance the absorption of graphene within a desired spectral window. Our calculations are based on Berreman's 4×4 method which treats anisotropic, isotropic and/ or inhomogeneous layered systems on equal footing.

  3. SYNTHESIS AND PROPERITIES OF SHISH-KEBAB-TYPE LIQUID CRYSTALLINE POLY(p-PHENYLENE)S

    Institute of Scientific and Technical Information of China (English)

    Shi-jun Zheng; Kazuo Akagi; Qun Xu; Zi-fa Li; Shao-kui Cao; Qi-feng Zhou

    2006-01-01

    The novel shish-kebab-type liquid crystalline poly(p-phenylene)s were synthesized through Suzuki coupling reaction from 2,5-bis[(4-n-alkoxyl)benzoyloxy]1,4-dibromobenzene (monomer 1) and 1,4-benzenediboronic acid bistrimethylene cyclic ester (monomer 2). Their structure and properties were characterized by GPC, DSC, X-ray diffraction and polarizing optical microscope (POM). It was found that the polymers turned to liquid crystalline phase above their melting point. The melting point (Tm) of the polymers decreases when the length of the alkoxy tails of the mesogenic units increases. The mesophase was identified by X-ray diffraction method. The polymers could dissolve in common organic solvents and show strong blue fluorescence. The maximum absorption bands of polymers prepared from annealed films have large red-shift due to the spontaneous orientation of the liquid crystalline side chains. The same phenomena were also observed in the fluorescence spectra.

  4. Viewing angle compensation of various LCD modes by using a liquid crystalline polymer film

    Science.gov (United States)

    Matsumoto, Takuya; Nishimura, Suzushi

    2013-09-01

    The authors have developed liquid crystalline retardation films to improve certain aspects of LCD image quality such as viewing angle performance and coloration. We have successfully created several types of optical retardation films using a rod-like liquid crystalline polymer. The resulting liquid crystalline polymer films have several advantages over conventional uni- or biaxially stretched retardation films. Precisely controlled structures such as twisted nematic, homogeneous nematic, hybrid nematic and homeotropic structures can provide ideal compensation of various LCD types, such as STN, TN, ECB, VA and IPS-LCDs. Twisted nematic film effectively prevents coloration of STN-LCDs, which is a critical flaw affecting color representation. Short pitch cholesteric film, which utilizes said rod-like liquid crystalline polymer and is the optical equivalent of a negative C-plate, can expand the viewing angle of VA-LCDs. Hybrid nematic film is quite unique in that the film functions not only as a wave plate but also as a viewing angle compensator for TN and ECB-LCDs. Homeotropic film, which acts as a positive-C plate, greatly improves the viewing angle performance of IPS and CPVA-LCDs. Our homeotropically aligned liquid crystalline film, called "NV film", is the world's thinnest retardation film. The thickness of the liquid crystalline layer is a mere 1 micrometer. Homeotropic film can be used to expand the viewing angle not only of LCDs but also OLED displays. And NV film, when used in in combination with a quarter wavelength plate, can expand the viewing angles of the circular polarizers used to prevent reflection in OLED displays.

  5. Supramolecular Liquid Crystallinity: Spherical Coils of Levan Surrounding Cylindrical Rods of DNA

    Science.gov (United States)

    Huber, Anne E.; Viney, Christopher

    1998-01-01

    Levan, which adopts a compact spherical conformation in aqueous solution, can form a liquid crystalline phase if DNA is also present. We propose that supramolecular rodlike structures, assembled by the noncovalent aggregation of levan around DNA, stabilize the lyotropic phase. We describe a geometric model for the aggregates. The model is quantitatively consistent with the relative amounts of DNA and levan needed for liquid crystallinity, and it agrees qualitatively with the shape of the boundary between the isotropic and heterogeneous fields on an experimentally determined phase diagram.

  6. SYNTHESIS AND CHARACTERIZATION OF PALLADIUM COORDINATING IMINE SIDE CHAIN LIQUID CRYSTALLINE POLYSILOXANES

    Institute of Scientific and Technical Information of China (English)

    CHEN Gang; ZHANG Rongben

    1991-01-01

    New thermotropic chloro-bridged dinuclear palladium coordinating imine side chain liquid crystalline polysiloxanes have been synthesized. Their mesomorphic properties have been investigated by DSC, X-ray diffraction and polarizing microscopy. The polymeric complexes show nematicdiscotic (Nd) mesophase. It is found that the temperature range of liquid crystalline state of chloro-bridged polymeric complexes is much wider than that of acetato-bridged ones and imine side chain polysiloxane. This indicates that the disc-like chloro-bridged palladium complexing units play a role as mesogen in mesophase.

  7. Optical microscopic observation of depletion layers, in a calamitic ferronematic lyomesophase

    OpenAIRE

    Liebert, L.; Figueiredo Neto, A.M.

    1984-01-01

    Inhomogenous magnetic grain concentrations giving depletion layers, theoretically predicted by Brochard and de Gennes were observed by optical microscopy in a calamitic ferronematic lyomesophase. These depletion layers were induced by orientation distortions inside walls where it is possible to visualize the inhomogenous concentration of magnetic grains.

  8. Mesomorphic properties of a bent-shaped liquid crystalline monomer

    Czech Academy of Sciences Publication Activity Database

    Novotná, Vladimíra; Baumeister, U.; Kohout, M.; Svoboda, J.

    2012-01-01

    Roč. 86, č. 5 (2012), 503-515. ISSN 0141-1594 R&D Projects: GA ČR(CZ) GAP204/11/0723 Institutional support: RVO:68378271 Keywords : liquid crystals * bent-shaped mesogen Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.863, year: 2012

  9. Synthesis and Supramolecular Chemistry of Novel Liquid Crystalline Crown Ether-Substituted Phthalocyanines : Toward Molecular Wires and Molecular Ionoelectronics

    NARCIS (Netherlands)

    Nostrum, Cornelus F. van; Picken, Stephen J.; Schouten, Arend-Jan; Nolte, Roeland J.M.

    1995-01-01

    The synthesis of the metal-free and the dihydroxysilicon derivatives of tetrakis[4’,5’-bis(decoxy)benzo-18-crown-6]phthalocyanine is described. The metal-free phthalocyanine is liquid crystalline and exhibits a crystalline phase to mesophase transition at 148 °C. The structures of the crystalline ph

  10. Electro-optics of novel polymer-liquid crystalline composites

    International Nuclear Information System (INIS)

    The polymer network liquid crystals based on the liquid crystals H37 and 5CB with PMVP and PEG have been developed. Mesogene substance HOBA is served for stabilization of obtaining composites. Kinetics of network formation is investigated by methods of polarization microscopy and integrated small-angle scattering. It is shown that gel-like states of the composite H-37+PMVP+HOBA and 5CB+PEG+HOBA are formed at polymer concentration above 7 percent and 9 percent, correspondingly. The basic electro-optic parameters of the obtained composites are determined at room temperature. Experimental results are explained by phase separation of the system, diminution of a working area of electro-optical effects and influence of areas with high polymer concentration on areas with their low concentration

  11. Side-chain liquid-crystalline polyesters for optical information storage

    DEFF Research Database (Denmark)

    Hvilsted, Søren; Andruzzi, F.; Ramanujam, P.S.

    1992-01-01

    We report erasable holographic recording with a resolution of at least 2500 lines/mm on unoriented films of side-chain liquid-crystalline polyesters. Recording energies of approximately 1 J/cm2 have been used. We have obtained a diffraction efficiency of approximately 30% with polarization...

  12. SYNTHESIS OF LIQUID CRYSTALLINE POLYACRYLATES WITH THIOESTER AS BRIDGE-BOND

    Institute of Scientific and Technical Information of China (English)

    ZHANG Weibang; ZHANG Guodong; XU Jiarui; ZENG Hanmin

    1996-01-01

    A new series of acrylates with the same mesogens containing thioester as bridge-bond were synthesized, and the acrylates were characterized by H1 NMR, IR and MS. The polymers were obtained by radical polymerization using AIBN as initiator. The monomers and polymers exhibit thermotropic-enantiotropic liquid crystalline behavior.

  13. Theoretical model of photoinduced anisotropy in liquid-crystalline azobenzene side-chain polyesters

    DEFF Research Database (Denmark)

    Pedersen, Thomas Garm; Johansen, Per Michael; Holme, N.C.R.;

    1998-01-01

    A theoretical framework for the temporal behavior of photoinduced anisotropy in liquid-crystalline azobenzene side-chain polyesters is constructed. The domain structure of the material is taken into account and inter molecular interactions are included through a mean-field description. Photoinduced...

  14. High diffraction efficiency polarization gratings recorded by biphotonic holography in an azobenzene liquid crystalline polyester

    DEFF Research Database (Denmark)

    Sánchez, C; Alcalá, R; Hvilsted, Søren;

    2001-01-01

    High diffraction efficiencies have been achieved with polarization gratings recorded in thin films of an azobenzene side-chain liquid crystalline polyester by means of biphotonic processes. Efficiency values up to 30% have been reached after an induction period of 300 s and subsequent evolution...

  15. Photoinduced anisotropy measurements in liquid-crystalline azobenzene side-chain polyesters

    DEFF Research Database (Denmark)

    Holme, NCR; Ramanujam, P.S.; Hvilsted, Søren

    1996-01-01

    Reversible photoinduced anisotropy in a series of Liquid-crystalline azobenzene side-chain polyesters is investigated as a function of intensity of the write beam and the sample temperature. Measurements reveal that the erasing takes place at a temperature much higher than the glass transition...... temperature. induced anisotropy can be erased by heating the polyesters to approximately 80 degrees C....

  16. STUDY ON THE PHASE TRANSITION KINETICS OF THERMOTROPIC LIQUID CRYSTALLINE AROMATIC-ALIPHATIC COPOLYESTER

    Institute of Scientific and Technical Information of China (English)

    LI Minhui; WANG Xiaogong; LIU Deshan; ZHOU Qixiang

    1991-01-01

    The phase transition kinetics of thermotropic liquid crystalline aromatic-aliphatic regular copolyester:(X) were studied by DSC. By means of Kissinger's method the kinetic equation and parameters including activation energy, rate order and preexponential factor for phase transition from nematic to isotropic were obtained. The activation energy from crystal to nematic was also presented.

  17. Electrophoretic Deposition for Cholesteric Liquid-Crystalline Devices with Memory and Modulation of Reflection Colors.

    Science.gov (United States)

    Tokunaga, Shoichi; Itoh, Yoshimitsu; Yaguchi, Yuya; Tanaka, Hiroyuki; Araoka, Fumito; Takezoe, Hideo; Aida, Takuzo

    2016-06-01

    The first design strategy that allows both memorization and modulation of the liquid-crystalline reflection color is reported. Electrophoretic deposition of a tailored ionic chiral dopant is key to realizing this unprecedented function, which may pave the way for the development of full-color e-paper that can operate without the need of color filters. PMID:27027423

  18. Liquid Crystalline π-Conjugated Copolymers Bearing a Pyrimidine Type Mesogenic Group

    Directory of Open Access Journals (Sweden)

    Kohsuke Kawabata

    2009-01-01

    Full Text Available Phenylene-thiophene-based liquid crystalline π-conjugated copolymers bearing mesogenic groups as side chains were synthesized via a Stille polycondensation reaction and confirmed to exhibit a nematic liquid crystal phase at appropriate temperatures. The formation of a nematic phase, but not a smectic phase indicates cooperation of the main chain and side chain in the formation of a nematic main-chain/side-chain liquid crystal phase. The generation of polarons in the main chain as charge carriers during in-situ vapor doping of iodine is confirmed to increase with a doping progresses, exhibiting Dysonian paramagnetic behavior typical of conductive polymers.

  19. Polarization axis-selective realignment of a photoreactive liquid crystalline composite with homogeneous alignment

    Science.gov (United States)

    Sasaki, Tomoyuki; Shoho, Takashi; Goto, Kohei; Sakamoto, Moritsugu; Noda, Kohei; Kawatsuki, Nobuhiro; Ono, Hiroshi

    2016-06-01

    We investigated the photoalignment properties of a liquid crystalline composite. The composite consisted of a low molecular weight nematic liquid crystal (LC) and a photoreactive liquid crystalline polymer containing 4-(4-methoxycinnamoyloxy)biphenyl side groups. Homogeneously aligned LC composite cells were fabricated using rubbed substrates and were then exposed to a linearly polarized (LP) ultraviolet (UV) laser beam. The alignment states of the LC composites were characterized using a LP visible laser beam. The LC composite in the cell was realigned by LP UV exposure and subsequent annealing. The direction of the realignment could be controlled by the polarization direction of the LP UV beam. The relationship between the realignment direction and the rubbing strength of the substrates was also investigated. A large realignment was induced in the LC composite cell when the azimuthal anchoring strength of the rubbed substrates was relatively weak.

  20. The microstructure of liquid immiscible Fe-Cu-based in situ formed amorphous/crystalline composite

    International Nuclear Information System (INIS)

    In the microstructures of slowly and rapidly cooled liquid of the immiscible alloy Fe30Cu32Ni10Si13Sn4B9Y2 two distinct regions were observed following arc melting and slow cooling, confirming that liquid/liquid phase separation had occurred. Rapid cooling from a temperature within the liquid immiscibility gap, melt spinning, resulted in an amorphous/crystalline composite, formed from the previously melted Fe- and Cu-rich regions, respectively. Transmission electron microscopic studies of this melt-spun ribbon revealed the glassy nature of the Fe-rich matrix, as well as of the Fe-rich spheres formed within the previously existing Cu-rich liquid

  1. Clustomesogens: Liquid Crystalline Hybrid Nanomaterials Containing Functional Metal Nanoclusters.

    Science.gov (United States)

    Molard, Yann

    2016-08-16

    Inorganic phosphorescent octahedral metal nanoclusters fill the gap between metal complexes and nanoparticles. They are finite groups of metal atoms linked by metal-metal bonds, with an exact composition and structure at the nanometer scale. As their phosphorescence internal quantum efficiency can approach 100%, they represent a very attractive class of molecular building blocks to design hybrid nanomaterials dedicated to light energy conversion, optoelectronic, display, lighting, or theragnostic applications. They are obtained as AnM6X(i)8X(a)6 ternary salt powders (A = alkali cation, M = Mo, Re, W, X(i): halogen inner ligand, X(a) = halogen apical ligand) by high temperature solid state synthesis (750-1200 °C). However, their ceramic-like behavior has largely restricted their use as functional components in the past. Since these last two decades, several groups, including ours, started to tackle the challenge of integrating them in easy-to-process materials. Within this context, we have extensively explored the nanocluster ternary salt specificities to develop a new class of self-organized hybrid organic-inorganic nanomaterials known as clustomesogens. These materials, combine the specific properties of nanoclusters (magnetic, electronic, luminescence) with the anisotropy-related properties of liquid crystals (LCs). This Account covers the research and development of clustomesogens starting from the design concepts and synthesis to their introduction in functional devices. We developed three strategies to build such hybrid super- or supramolecules. In the covalent approach, we capitalized on the apical ligand-metal bond iono-covalent character to graft tailor-made organic LC promoters on the {M6X(i)8}(n+) nanocluster cores. The supramolecular approach relies on the host-guest complexation of the ternary cluster salt alkali cations with functional crown ether macrocycles. We showed that the hybrid LC behavior depends on the macrocycles structural features

  2. X-ray diffraction study of thermotropic liquid crystalline polyesters and diester model compounds

    Science.gov (United States)

    Chin, H. H.; Azaroff, L. V.; Griffin, A. C.

    1987-10-01

    Two nematic liquid crystalline polyesters were examined by X-ray diffraction following quenching from the nematic temperature in a magnetic field of 15 tesla. It was not possible to quench an aligned nematic glass; instead a polycrystalline phase showing some preferred orientation or an unoriented nematic melt yielded monodomain nematic diffraction patterns with one resembling that of a fiber (crystalline) photograph while the other showed good nematic alignment which could be enhanced slightly by annealing. A series of Siamese-twin diester model compounds also examined at their respective nematic temperatures in a magnetic field of compounds also were examined at their crystalline phase at room temperature. All displayed well-aligned nematic monodomains above the crystallization point.

  3. Single cell-gap transflective liquid crystal device created by controlling the pretilt angle using a liquid crystalline reactive monomer.

    Science.gov (United States)

    Jeon, Eun-Young; Kim, Ki-Han; Lee, Ji-Hoon; Yoon, Tae-Hoon

    2011-12-01

    We present a single cell-gap transflective liquid crystal (LC) device using a homogeneous alignment polyimide (H-PI) mixed with a liquid crystalline reactive monomer that is able to vertically align the LC. We obtain two different pretilt angles in each pixel through the region by region control of the UV exposure time. The smaller pretilt angle is used to obtain a half-wave phase retardation for the transmissive part, whereas the larger pretilt angle is used to obtain a quarter-wave phase retardation for the reflective part. PMID:22273954

  4. Shear Flow Induced Transition from Liquid-Crystalline to Polymer Behavior in Side-Chain Liquid Crystal Polymers

    Science.gov (United States)

    Noirez, L.; Lapp, A.

    1997-01-01

    We determine the structure and conformation of side-chain liquid-crystalline polymers subjected to shear flow in the vicinity of the smectic phase by neutron scattering on the velocity gradient plane. Below the nematic-smectic transition we observe a typical liquid-crystal behavior; the smectic layers slide, leading to a main-chain elongation parallel to the velocity direction. In contrast, a shear applied above the transition induces a tilted main-chain conformation which is typical for polymer behavior.

  5. Synthesis of rod-like bis-ester liquid crystals and their influence on photoelectric properties of liquid crystalline materials

    Institute of Scientific and Technical Information of China (English)

    Min Yan Zheng; Yong Sheng Wei; Zhong Wei An; Shan Wang

    2009-01-01

    Six novel rod-like magnetic liquid crystals have been prepared,in which trans-bicyclobexyl or trans-cyclobexylphenyl and biphenylcarboxylic acid phenyl ester mesogenic cores with n-propyl and n-pentyl substituents were terminated by 4-hydroxylTEMPO (TEMPO = 2,2,6,6-tetramethylpiperidine-l-oxy).Their structures were confirmed by elemental analysis,IR and MS.Determined by SQUID,EPR,DSC and HS-POM (heat stage polarizing optical microscope),the six compounds all have both magnetic and liquid crystalline properties; their temperature ranges of mesophase were from 16.0 to 24.8 ~C,and the magnetic liquid crystal molecules could obviously improve the response sensitivity of liquid crystal materials.

  6. Polarization holographic grating recording in a liquid crystalline azo dye copolymer with hidden helical superstructure

    International Nuclear Information System (INIS)

    The polarization holographic grating recording in a liquid crystalline photopolymer with hidden helical superstructure (P8*NN) is reported. It has been demonstrated that this photosensitive polymer could be utilized both for the recording of both the amplitude and the polarization holographic gratings. Diffraction efficiency of several diffraction orders (up to ±4 orders) has been measured for different intensities of the recording light beams. A detailed investigation was devoted to the polarization holographic recording. It is shown that the diffraction efficiency strongly depends on the polarization state of the probing He-Ne laser beam. The maximum achieved diffraction efficiency (for +1 order) was about 30%. The possible mechanisms responsible for the grating recording are trans-cis isomerization and photo-orientation of liquid crystalline terminal ends. This material with highly efficient polarization gratings is promising for polarimetric and interferomeric applications.

  7. REVIEWS OF TOPICAL PROBLEMS: Supermolecular liquid-crystalline structures in solutions of amphiphilic molecules

    Science.gov (United States)

    Vedenov, A. A.; Levchenko, E. B.

    1983-09-01

    This paper reviews the physical properties of liquid-crystalline phases arising in solutions containing molecules of amphiphilic substances. The basic characteristics of micelle formation in dilute solutions, models of sphere-disk or sphere-cylinder structural transformations, as well as phase transitions related to the appearance of lyotropic mesophases in the system, including nematic, lamellar, hexagonal, and others, are examined. The results of experimental and theoretical investigation of "solvation" forces acting between micelles in the solvent, as well as recently studied models of swelling of lamellar phases are presented. The phenomena occurring near the inversion point of microemulsions in amphiphile-oil-water systems are examined briefly. The role of liquid-crystalline ordering in some biological systems is discussed.

  8. Self-assembly of azobenzene based side-chain liquid crystalline polymer and -alkyloxybenzoic acids

    Indian Academy of Sciences (India)

    Kumarasamy Gayathri; Subramanian Balamurugan; Palaninathan Kannan

    2011-05-01

    Liquid crystalline pendant polymeric complexes have been obtained by supramolecular assembly of two mesogenic components namely, poly[4-(10-acryloyloxydecyloxy)-4'- phenylazobenzonitrile] (P10) and 4-alkyloxybenzoic acids (A7-A12). Hydrogen bond formed between carboxylic acid and cyano moiety served as molecular bridge. The polymeric complexes acquitted as undivided liquid crystalline properties exhibited stable and enantiotropic mesophases. The precursor, monomer and polymer were analysed by 1H-NMR and 13C-NMR spectroscopy. The hydrogen bonding interaction in polymer complexes (P10-A7 to P10-A12) was investigated by FT-IR spectroscopy. The thermal behaviours and textural analysis were studied by differential scanning calorimetry and polarized optical microscopy respectively.

  9. Liquid crystalline polymer nanocomposites reinforced with in-situ reduced graphene oxide

    Directory of Open Access Journals (Sweden)

    D. Pedrazzoli

    2015-08-01

    Full Text Available In this work liquid-crystalline polymer (LCP nanocomposites reinforced with in-situ reduced graphene oxide are investigated. Graphene oxide (GO was first synthesized by the Hummers method, and the kinetics of its thermal reduction was assessed. GO layers were then homogeneously dispersed in a thermotropic liquid crystalline polymer matrix (Vectran®, and an in-situ thermal reduction of GO into reduced graphene oxide (rGO was performed. Even at low rGO amount, the resulting nanocomposites exhibited an enhancement of both the mechanical properties and the thermal stability. Improvements of the creep stability and of the thermo-mechanical behavior were also observed upon nanofiller incorporation. Furthermore, in-situ thermal reduction of the insulating GO into the more electrically conductive rGO led to an important surface resistivity decrease in the nanofilled samples.

  10. Synthesis and mesomorphic properties of calamitic malonates and cyanoacetates tethered to 4-cyanobiphenyls

    Directory of Open Access Journals (Sweden)

    Katharina C. Kress

    2012-03-01

    Full Text Available 4-Cyano-1,1'-biphenyl derivatives bearing ω-hydroxyalkyl substituents were reacted with methyl 3-chloro-3-oxopropionate or cyanoacetic acid, giving liquid-crystalline linear malonates and cyanoacetates. These compounds formed monotropic nematic phases at 62 °C down to ambient temperature upon cooling from the isotropic liquid. The mesomorphic properties were investigated by differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction (WAXS.

  11. Investigations on the liquid crystalline phases of cation-induced condensed DNA

    Indian Academy of Sciences (India)

    C K S Pillai; Neethu Sundaresan; M Radhakrishnan Pillai; T Thomas; T J Thomas

    2005-10-01

    Viral and nonviral condensing agents are used in gene therapy to compact oligonucleotides and plasmid DNA into nanostructures for their efficient transport through the cell membranes. Whereas viral vectors are best by the toxic effects on the immune system, most of the nonviral delivery vehicles are not effective for use in clinical system. Recent investigations indicate that the supramolecular organization of DNA in the condensed state is liquid crystalline. The present level of understanding of the liquid crystalline phase of DNA is inadequate and a thorough investigation is required to understand the nature, stability, texture and the influence of various environmental conditions on the structure of the phase. The present study is mainly concerned with the physicochemical investigations on the liquid crystalline transitions during compaction of DNA by cationic species such as polyamines and metallic cations. As a preliminary to the above investigation, studies were conducted on the evolution of mesophase transitions of DNA with various cationic counterion species using polarized light microscopy. These studies indicated significant variations in the phase behaviour of DNA in the presence of Li and other ions. Apart from the neutralization of the charges on the DNA molecule, these ions are found to influence selectively the hydration sphere of DNA that in turn influences the induction and stabilization of the LC phases. The higher stability observed with the liquid crystalline phases of Li-DNA system could be useful in the production of nanostructured DNA. In the case of the polyamine, a structural specificity effect depending on the nature, charge and structure of the polyamine used has been found to be favoured in the crystallization of DNA.

  12. First ferrocene-containing low molar mass organosiloxane liquid-crystalline materials

    OpenAIRE

    Coles, Harry, J.; Meyer, Sebastien; Lehmann, Petra; Deschenaux, Robert; Jauslin, Isabelle

    2010-01-01

    Two ferrocene-containing low molar mass organosiloxane liquid-crystalline materials have been synthesised and their phase-transition behaviour investigated. The ω-unsaturated ferrocene precursor was hydrosilylated by addition of pentamethyldisiloxane or heptamethyltrisiloxane in the presence of platinum divinyltetramethyldisiloxane complex. The ferrocene precursor presents smectic A and smectic C phases; the disiloxane compound exhibits a smectic C phase; the trisiloxane compound shows a smec...

  13. Investigations on the liquid crystalline phases of cation-induced condensed DNA

    Science.gov (United States)

    Pillai, C. K. S.; Sundaresan, Neethu; Radhakrishnan Pillai, M.; Thomas, T.; Thomas, T. J.

    2005-10-01

    Viral and nonviral condensing agents are used in gene therapy to compact oligonucleotides and plasmid DNA into nanostructures for their efficient transport through the cell membranes. Whereas viral vectors are best by the toxic effects on the immune system, most of the nonviral delivery vehicles are not effective for use in clinical system. Recent investigations indicate that the supramolecular organization of DNA in the condensed state is liquid crystalline. The present level of understanding of the liquid crystalline phase of DNA is inadequate and a thorough investigation is required to understand the nature, stability, texture and the influence of various environmental conditions on the structure of the phase. The present study is mainly concerned with the physico-chemical investigations on the liquid crystalline transitions during compaction of DNA by cationic species such as polyamines and metallic cations. As a preliminary to the above investigation, studies were conducted on the evolution of mesophase transitions of DNA with various cationic counterion species using polarized light microscopy. These studies indicated significant variations in the phase behaviour of DNA in the presence of Li and other ions. Apart from the neutralization of the charges on the DNA molecule, these ions are found to influence selectively the hydration sphere of DNA that in turn influences the induction and stabilization of the LC phases. The higher stability observed with the liquid crystalline phases of Li--DNA system could be useful in the production of nanostructured DNA. In the case of the polyamine, a structural specificity effect depending on the nature, charge and structure of the polyamine used has been found to be favoured in the crystallization of DNA.

  14. Ferroelectric liquid-crystalline side group polymers - spacer length variation and comparison with the monomers

    OpenAIRE

    Kühnpast, Kurt; Springer, Jürgen; Scherowsky, Günter; Gießelmann, Frank; Zugenmaier, Peter

    1993-01-01

    The phase behaviour and the ferroelectric properties of liquid-crystalline side group polyacrylates containing an (R)-4''(1-methylheptyloxy)-4'-biphenylyloxycarbonyl-4-phenoxy moiety are compared with the properties of their monomers. A S*C phase polymorphism including monolayer and bilayer structures was found for the polymers. Some of the S*C subphases, consisting of smectic mono- or bi-layers, do not exhibit ferroelectric properties. These unusual properties do not exist for the correspond...

  15. SYNTHESIS AND CHARACTERIZATION OF TRIAZOLE CONTAINING LIQUID CRYSTALLINE POLYMERS THROUGH 1,3-DIPOLAR CYCLOADDITION POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    Devamani; Srividhya; Sundaram; Manjunathan; Sivashankaran; Nithyanandan; Subramanan; Balamurugan; Sengodan; Senthil

    2009-01-01

    Liquid crystalline polymers containing 1,2,3-triazole units as linking groups have been synthesized from the monomers containing triad ester diazide and flexible dialkyne ester by 1,3-cycloaddition reaction and were characterized. Click reaction of azide and alkyne functionals catalyzed by Cu(I) yielded target polyesters with 1,2,3-triazole groups.The structure of the polymer was confirmed by spectral techniques.GPC analysis reveals that the polymers have moderate molecular weight with narrow distributio...

  16. Side-chain liquid-crystalline polyesters for optical information storage

    DEFF Research Database (Denmark)

    Hvilsted, Søren; Andruzzi, F.; Ramanujam, P.S.

    1992-01-01

    We report erasable holographic recording with a resolution of at least 2500 lines/mm on unoriented films of side-chain liquid-crystalline polyesters. Recording energies of approximately 1 J/cm2 have been used. We have obtained a diffraction efficiency of approximately 30% with polarization record...... recording of holograms. The holograms can be erased by heating them to approximately 80-degrees-C for approximately 2 min and are available for rerecording....

  17. Liquid-Crystalline Thiol- and Disulfide-Based Dendrimers for the Functionalization of Gold Nanoparticles

    OpenAIRE

    Frein, Stéphane; Boudon, Julien; Vonlanthen, Mireille; Scharf, Toral; Barberá, Joaquín; Süss-Fink, Georg; Bürgi, Thomas; Deschenaux, Robert

    2009-01-01

    Liquid-crystalline dendrons carrying either a thiol or disulfide function which display nematic, smectic A, columnar, or chiral nematic phases have been synthesized. Their mesomorphic properties are in agreement with the nature of the mesogenic units and structure of the dendrons. The first-generation poly(aryl ester) dendron containing two cyanobiphenyl mesogenic units was used to functionalize gold nanoparticles. For full coverage, a smectic-like supramolecular organization on the nanometer...

  18. Crystalline Silicotitanate: a New Type of Ion Exchanger for Cs Removal from Liquid Waste

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The research and developments of a new type of inorganic ion exchanger, crystalline silicotitanate (CST) are reviewed.This material is stable against radiation, and the CST has high selectivity for Cs over Na, K and Rb. It performs well in acidic, neutral, and basic solutions. The results of ion exchange tests show that CST is an excellent candidate for Cs removal from high-level liquid waste.

  19. Studies on The Transient Shear-Flow Behavior Of Liquid-Crystalline Polymers

    OpenAIRE

    Viola, G. G.; Baird, Donald G.

    1986-01-01

    An understanding of the flow behavior of liquid crystalline polymers (LCP's) is of immense practical value because of the potential to form high modulus materials from these polymers. These fluids exhibit a high degree of structure even in the quiescent state, as evidenced by their ability to transmit polarized light. In an effort to understand how the structure changes during flow, we have carried out a study on the transient shear flow properties of two thermotropic copolyesters of 60_ and ...

  20. Co-rotational Oldroyd Fluid B Model for Spinning Flow of Liquid Crystalline Polymer

    Institute of Scientific and Technical Information of China (English)

    付强

    2003-01-01

    The relationship between the extensional viscosity and material parameters was studied through the analytical formulas of stress and extensional viscosity. The differential equations were solved to obtain the relationship between extensional viscosity and strain rates. The results obtained qualitatively agree with the experimental results. The study makes it practicable to simulate the rheologic behaviors of spinning flow of liquid crystalline polymer using co-rotational Oldroyd fluid B model.

  1. Transient Flow Of Thermotropic Liquid-Crystalline Polymers in Step Strain Experiments

    OpenAIRE

    Done, D.; Baird, Donald G.

    1990-01-01

    The transient response of two thermotropic liquid crystalline polymers (a copolyester of 60 mol_% p_hydroxybenzoic acid, PHB, and 40 mol_% poly(ethylene terephthalate), PET, and a copolyester of PHB and 2_hydroxy_6_naphthoic acid, following step strains up to 20 strain units was measured. The relaxation curves typically show an initially rapid decay followed by a long relaxation tail. The lower the temperature, the more remarkable is the length of the long relaxation tail. This behavior makes...

  2. The rheology and structure of thermotropic liquid crystalline polymers in extensional flow

    OpenAIRE

    Wilson, Thomas Stephen

    1991-01-01

    The transient shear and elongational flow behavior of HPC EF, G, and HBA/HNA (Vectra A9W) have been measured in order to determine the behavior of liquid crystalline polymer systems and to establish whether this behavior is different from that for isotropic flexible-chain polymer melts and isotropic systems of rodlike polymers. In order to accomplish this a rotary clamp extensional rheometer was constructed which is capable of measuring the elongational flow behavior of polymer melts up to 32...

  3. Stochastic semi-Lagrangian micro–macro calculations of liquid crystalline solutions in complex flows

    OpenAIRE

    Prieto Ortiz, Juan Luis; Bermejo Bermejo, Rodolfo; Laso Carbajo, Manuel

    2010-01-01

    A general method for the simulation of complex flows of liquid crystalline polymers (LCPs) using a stochastic semi-Lagrangian micro–macro method is introduced. The macroscopic part uses a spatial-temporal second order accurate semi-Lagrangian algorithm, where ideas from the finite element and natural element methods are mixed in order to compute average quantities. The microscopic part employs a stochastic interpretation of the Doi–Hess LCP model, which is discretized with a second order Rich...

  4. Ophthalmic Delivery of Brinzolamide by Liquid Crystalline Nanoparticles: In Vitro and In Vivo Evaluation

    OpenAIRE

    Wu, Weijun; Li, Jing; Wu, Lin; Wang, Baoyan; Wang, Zhongyuan; Xu, Qunwei; Xin, Hongliang

    2013-01-01

    Brinzolamide (BLZ) is a drug used to treat glaucoma; however, its use is restricted due to some unwanted adverse events. The goal of this study was to develop BLZ-loaded liquid crystalline nanoparticles (BLZ LCNPs) and to figure out the possibility of LCNPs as a new therapeutic system for glaucoma. BLZ LCNPs were produced by a modified emulsification method and their physicochemical aspects were estimated. In vitro release study revealed BLZ LCNPs displayed to some extent prolonged drug relea...

  5. Control of structure and growth of polymorphic crystalline thin films of amphiphilic molecules on liquid surfaces

    DEFF Research Database (Denmark)

    Weinbach, S.P.; Kjær, K.; Bouwman, W.G.;

    1994-01-01

    The spontaneous formation and coexistence of crystalline polymorphic trilayer domains in amphiphilic films at air-liquid interfaces is demonstrated by grazing incidence synchrotron x-ray diffraction. These polymorphic crystallites may serve as models for the early stages of crystal nucleation and...... growth, helping to elucidate the manner in which additives influence the progress of crystal nucleation, growth, and polymorphism and suggesting ways of selectively generating and controlling multilayers on liquid surfaces. Auxiliary molecules have been designed to selectively inhibit development of the...

  6. Designing solution-processable air-stable liquid crystalline crosslinkable semiconductors

    DEFF Research Database (Denmark)

    McCulloch, I.; Bailey, C.; Genevicius, K.;

    2006-01-01

    will typically be of lower performance than those using the present state of the art single crystal or polysilicon transistors, but comparable to amorphous silicon. A range of prototypes are under development, including rollable electrophoretic displays, active matrix liquid crystal (LC) displays, flexible...... to facilitate charge transport and provide good oxidative stability, were prepared and their liquid crystalline properties evaluated. The organization and alignment of the mesogens, both before and after crosslinking, were probed by grazing incidence wide-angle X-ray scattering of thin films. Both time...

  7. Electrooptical properties of hybrid liquid crystalline systems containing CdSe quantum dots

    Science.gov (United States)

    Dradrach, K.; Bartkiewicz, S.; Miniewicz, A.

    2014-12-01

    In this paper, we present electrooptical properties of hybrid liquid crystalline systems, which contained CdSe quantum dots (QDs). We have shown by experiments of degenerated two-wave mixing and transverse conductivity measurements that liquid crystal cells filled with nematic and doped with semiconductor nanoparticles exhibit photorefractive effect associated with photoconductivity appearing in the system. We also present the mathematical model, which explains the relationship between the photoconductivity of the layer on which the QDs reside and the generation of holographic gratings. Our research may help to develop better understanding of processes observed in such systems and create more efficient materials for holographic data storage.

  8. Electrooptical properties of hybrid liquid crystalline systems containing CdSe quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Dradrach, K., E-mail: klaudia.dradrach@pwr.edu.pl; Bartkiewicz, S.; Miniewicz, A. [Department of Chemistry, Institute of Physical and Theoretical Chemistry, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw (Poland)

    2014-12-08

    In this paper, we present electrooptical properties of hybrid liquid crystalline systems, which contained CdSe quantum dots (QDs). We have shown by experiments of degenerated two-wave mixing and transverse conductivity measurements that liquid crystal cells filled with nematic and doped with semiconductor nanoparticles exhibit photorefractive effect associated with photoconductivity appearing in the system. We also present the mathematical model, which explains the relationship between the photoconductivity of the layer on which the QDs reside and the generation of holographic gratings. Our research may help to develop better understanding of processes observed in such systems and create more efficient materials for holographic data storage.

  9. From Cellulosic Based Liquid Crystalline Sheared Solutions to 1D and 2D Soft Materials

    Directory of Open Access Journals (Sweden)

    Maria Helena Godinho

    2014-06-01

    Full Text Available Liquid crystalline cellulosic-based solutions described by distinctive properties are at the origin of different kinds of multifunctional materials with unique characteristics. These solutions can form chiral nematic phases at rest, with tuneable photonic behavior, and exhibit a complex behavior associated with the onset of a network of director field defects under shear. Techniques, such as Nuclear Magnetic Resonance (NMR, Rheology coupled with NMR (Rheo-NMR, rheology, optical methods, Magnetic Resonance Imaging (MRI, Wide Angle X-rays Scattering (WAXS, were extensively used to enlighten the liquid crystalline characteristics of these cellulosic solutions. Cellulosic films produced by shear casting and fibers by electrospinning, from these liquid crystalline solutions, have regained wider attention due to recognition of their innovative properties associated to their biocompatibility. Electrospun membranes composed by helical and spiral shape fibers allow the achievement of large surface areas, leading to the improvement of the performance of this kind of systems. The moisture response, light modulated, wettability and the capability of orienting protein and cellulose crystals, opened a wide range of new applications to the shear casted films. Characterization by NMR, X-rays, tensile tests, AFM, and optical methods allowed detailed characterization of those soft cellulosic materials. In this work, special attention will be given to recent developments, including, among others, a moisture driven cellulosic motor and electro-optical devices.

  10. Crystalline and liquid Si3 N4 characterization by first-principles molecular dynamics simulations

    Science.gov (United States)

    Mauri, Aurelio; Celino, Massimo; Castellani, Niccoló; Erbetta, Davide

    2011-05-01

    Silicon nitride (Si3 N4) has a wide range of engineering applications where its mechanical and electronic properties can be effectively exploited. In particular, in the microelectronics field, the amorphous silicon nitride films are widely used as charge storage layer in metal-alumina-nitrideoxide nonvolatile memory devices. Atomic structure of amorphous silicon nitride is characterized by an high concentration of traps that control the electric behavior of the final device by the trappingde-trapping mechanism of the electrical charge occurring in its traps. In order to have a deep understanding of the material properties and, in particular, the nature of the electrical active traps a detailed numerical characterization of the crystalline and liquid phases is mandatory. For these reasons first-principles molecular dynamics simulations are extensively employed to simulate the crystalline Si3 N4 in its crystalline and liquid phases. Good agreement with experimental results is obtained in terms of density and formation entalpy. Detailed characterization of c-Si3 N4 electronic properties is performed in terms of band structure and band gap. Then constant temperature and constant volume first-principles molecular dynamics is used to disorder a stoichiometric sample of Si3 N4 . Extensive molecular dynamics simulations are performed to obtain a reliable liquid sample whose atomic structure does not depend on the starting atomic configuration. Detailed characterization of the atomic structure is achieved in terms of radial distribution functions and total structure factor.

  11. SYNTHESIS AND CHARACTERIZATION OF SIDE CHAIN LIQUID CRYSTALLINE POLYSILOXANES CONTAINING BENZYL ETHER LINKING UNITS

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    Side chain liquid crystalline polysiloxanes containing benzyl ether linking units were synthesized by the hydrosilylation of poly(methylhydrosiloxane) with a series of 4-(4-alkoxybenzyloxy)-4'-allyloxybiphenyl monomers [4-(4-methoxybenzyloxy)-4'-allyloxybiphenyl (M1), 4-(4-ethoxybenzyloxy)-4'-allyloxybiphenyl (M2), 4-(4-propoxybenzyloxy)-4'-allyloxybiphenyl (M3), 4-(4-butoxybenzyloxy)-4'-allyloxybiphenyl (M4), 4-(4-pentoxybenzyloxy)-4'-allyloxybiphenyl (Ms), 4-benzyloxy-4'-allyloxybiphenyl (M6)]. The phase behavior of monomeric and polymeric liquid crystals was characterized by differential scanning calorimetry and optical polarization microscopy where the groups are ranged from methoxy to pentoxy. Both the monomeric and polymeric liquid crystals exhibit liquid crystal behaviors.

  12. SYNTHESIS AND SUPRAMOLECULAR CHEMISTRY OF NOVEL LIQUID-CRYSTALLINE CROWN ETHER-SUBSTITUTED PHTHALOCYANINES - TOWARD MOLECULAR WIRES AND MOLECULAR IONOELECTRONICS

    NARCIS (Netherlands)

    VANNOSTRUM, CF; PICKEN, SJ; SCHOUTEN, AJ; NOLTE, RJM

    1995-01-01

    The synthesis of the metal-free and the dihydroxysilicon derivatives of tetrakis[4',5'-bis(decoxy)benzo-18-crown-6]phthalocyanine is described. The metal-free phthalocyanine is liquid crystalline and exhibits a crystalline phase to mesophase transition at 148 degrees C. The structures of the crystal

  13. Effect of Flame Conditions on Crystalline Structure of TiO2 in Liquid Flame Spraying

    Institute of Scientific and Technical Information of China (English)

    LI Chang-jiu; YANG Guan-jun; WANG Yu-yue

    2004-01-01

    Nanostructured TiO2 is a most promising functional ceramic owing to its potential utilization in photocatalytical, optical and electrical applications. Nanostructured TiO2 coating was deposited through thermal spraying with liquid feedstock. Two types of crystalline structures were present in the synthesized TiO2 coating including anatase phase and rutile phase.The effect of spray flame conditions on the crystalline structure was investigated in order to control the crystalline structure of the coating. The results showed that spray distance, flame power and precursor concentration in the liquid feedstock significantly influenced phase constitutions and grain size in the coating. Anatase phase was formed at spray distance from 150 to 250mm, while rutile phase was evidently observed in the coating deposited at 100 mm. The results suggested that anatase phase was firstly formed in the coating, and rutile phase resulted from the transformation of the deposited anatase phase. The phase transformation from anatase to rutile occurred through the annealing effect of spraying flame. The control of the phase formation can be realized through flame condition and spray distance.

  14. Method for forming single phase, single crystalline 2122 BCSCO superconductor thin films by liquid phase epitaxy

    Science.gov (United States)

    Pandey, Raghvendra K. (Inventor); Raina, Kanwal (Inventor); Solayappan, Narayanan (Inventor)

    1994-01-01

    A substantially single phase, single crystalline, highly epitaxial film of Bi.sub.2 CaSr.sub.2 Cu.sub.2 O.sub.8 superconductor which has a T.sub.c (zero resistance) of 83 K is provided on a lattice-matched substrate with no intergrowth. This film is produced by a Liquid Phase Epitaxy method which includes the steps of forming a dilute supercooled molten solution of a single phase superconducting mixture of oxides of Bi, Ca, Sr, and Cu having an atomic ratio of about 2:1:2:2 in a nonreactive flux such as KCl, introducing the substrate, e.g., NdGaO.sub.3, into the molten solution at 850.degree. C., cooling the solution from 850.degree. C. to 830.degree. C. to grow the film and rapidly cooling the substrate to room temperature to maintain the desired single phase, single crystalline film structure.

  15. Vitrified chiral-nematic liquid crystalline films for selective reflection and circular polarization

    Energy Technology Data Exchange (ETDEWEB)

    Katsis, D.; Chen, P.H.M.; Mastrangelo, J.C.; Chen, S.H. [Univ. of Rochester, NY (United States); Blanton, T.N. [Eastman Kodak Co., Rochester, NY (United States)

    1999-06-01

    Nematic and left-handed chiral-nematic liquid crystals comprising methoxybiphenylbenzoate and (S)-(-)-1-phenylethylamine pendants to a cyclohexane core were synthesized and characterized. Although pristine samples were found to be polycrystalline, thermal quenching following heating to and annealing at elevated temperatures permitted the molecular orders characteristic of liquid crystalline mesomorphism to be frozen in the glassy state. Left at room temperature for 6 months, the vitrified liquid crystalline films showed no evidence of recrystallization. An orientational order parameter of 0.65 was determined with linear dichroism of a vitrified nematic film doped with Exalite 428 at a mole fraction of 0.0025. Birefringence dispersion of a blank vitrified nematic film was determined using a phase-difference method complemented by Abbe refractometry. A series of vitrified chiral-nematic films were prepared to demonstrate selective reflection and circular polarization with a spectral region tunable from blue to the infrared region by varying the chemical composition. The experimentally measured circular polarization spectra were found to agree with the Good-Karali theory in which all four system parameters were determined a priori: optical birefringence, average refractive index, selective reflection wavelength, and film thickness.

  16. Dynamical Study of Guest-Host Orientational Interaction in LiquidCrystalline Materials

    Energy Technology Data Exchange (ETDEWEB)

    Truong, Thai Viet

    2005-12-20

    Guest-host interaction has long been a subject of interest in many disciplines. Emphasis is often on how a small amount of guest substance could significantly affect the properties of a host material. This thesis describe our work in studying a guest-host effect where dye-doping of liquid crystalline materials greatly enhances the optical Kerr nonlinearity of the material. The dye molecules, upon excitation and via intermolecular interaction, provides an extra torque to reorient the host molecules, leading to the enhanced optical Kerr nonlinearity. We carried out a comprehensive study on the dynamics of the photoexcited dye-doped liquid crystalline medium. Using various experimental techniques, we separately characterized the dynamical responses of the relevant molecular species present in the medium following photo-excitation, and thus were able to follow the transient process in which photo-excitation of the dye molecules exert through guest-host interaction a net torque on the host LC material, leading to the observed enhanced molecular reorientation. We also observed for the first time the enhanced reorientation in a pure liquid crystal system, where the guest population is created through photoexcitation of the host molecules themselves. Experimental results agree quantitatively with the time-dependent theory based on a mean-field model of the guest-host interaction.

  17. Crystalline and liquid Si3 N4 characterization by first-principles molecular dynamics simulations

    Directory of Open Access Journals (Sweden)

    Castellani Niccoló

    2011-05-01

    Full Text Available Silicon nitride (Si3 N4 has a wide range of engineering applications where its mechanical and electronic properties can be effectively exploited. In particular, in the microelectronics field, the amorphous silicon nitride films are widely used as charge storage layer in metal-alumina-nitrideoxide nonvolatile memory devices. Atomic structure of amorphous silicon nitride is characterized by an high concentration of traps that control the electric behavior of the final device by the trappingde-trapping mechanism of the electrical charge occurring in its traps. In order to have a deep understanding of the material properties and, in particular, the nature of the electrical active traps a detailed numerical characterization of the crystalline and liquid phases is mandatory. For these reasons first-principles molecular dynamics simulations are extensively employed to simulate the crystalline Si3 N4 in its crystalline and liquid phases. Good agreement with experimental results is obtained in terms of density and formation entalpy. Detailed characterization of c-Si3 N4 electronic properties is performed in terms of band structure and band gap. Then constant temperature and constant volume first-principles molecular dynamics is used to disorder a stoichiometric sample of Si3 N4 . Extensive molecular dynamics simulations are performed to obtain a reliable liquid sample whose atomic structure does not depend on the starting atomic configuration. Detailed characterization of the atomic structure is achieved in terms of radial distribution functions and total structure factor.

  18. Hybrid organic–inorganic UV-cured films containing liquid-crystalline units

    Energy Technology Data Exchange (ETDEWEB)

    Giamberini, M. [Universitat Rovira i Virgili, Departament de Enginyeria Química, Av. Països Catalans, 26, 43007 Tarragona (Spain); Malucelli, G., E-mail: giulio.malucelli@polito.it [Politecnico di Torino, Dipartimento di Scienza Applicata e Tecnologia, Viale T. Michel 5, 15121 Alessandria (Italy)

    2013-12-02

    Hybrid organic–inorganic films have been prepared through a dual-cure process, involving photopolymerization (UV-curing) of a methacrylic resin and hydrolysis/condensation of alkoxysilane groups, in the presence of three different liquid crystalline oligomers bearing acrylic reactive groups and synthesized on purpose. These UV-curable mixtures have been coated on glass substrates, exposed to UV radiation in inert (nitrogen) atmosphere, then thermally treated in order to promote the occurrence of the sol–gel reaction and finally peeled off from the substrate. The morphology of the obtained films has been investigated by means of scanning electron microscopy, environmental scanning electron microscopy and atomic force microscopy measurements. Significant silica enrichment on the “gas side” of the films (i.e. the side exposed to the UV-radiation) has been found, as well as the occurrence of the formation of interesting silica conical shapes on the same side with respect to the glass counterpart. Because of the constraints exerted by the inorganic domains on the mobility of the polymer chains, the T{sub g} values of the obtained networks have been found to increase in the presence of the silica phases, which also might have contributed to the occurrence of segregation phenomena of the liquid crystalline phases. - Highlights: • Three liquid-crystalline (LC) acrylic oligomers were synthesized. • Hybrid organic–inorganic films containing the LC units were prepared. • An asymmetric distribution of silica on the surfaces of the films was assessed. • Silica conical shapes preferably on one side of the hybrid LC films were formed.

  19. Highly polarized emission of the liquid crystalline conjugated polymer by controlling the surface anchoring energy

    Science.gov (United States)

    In Jo, Soo; Kim, Youngsik; Baek, Ji-Ho; Yu, Chang-Jae; Kim, Jae-Hoon

    2014-01-01

    We demonstrated a highly polarized organic light-emitting diode (OLED) through the enhancement of the orientational ordering of the emitting polymer with a nematic liquid crystalline (LC) phase. The highly ordered state of the conjugate polymer was obtained by thermal annealing at the nematic temperature and strong azimuthal anchoring energy of the underlying polyimide. The order parameter of the conjugate polymer was analyzed using a second-harmonic generation model and the dichroic ratio was measured to be 22 : 1. Also, we applied our optimized OLED with high optical polarizability to an effective light source for a twisted nematic LC display.

  20. Finite-difference time-domain analysis of light propagation in cholesteric liquid crystalline droplet array

    Science.gov (United States)

    Yamamoto, Kaho; Iwai, Yosuke; Uchida, Yoshiaki; Nishiyama, Norikazu

    2016-08-01

    We numerically analyzed the light propagation in cholesteric liquid crystalline (CLC) droplet array by the finite-difference time-domain (FDTD) method. The FDTD method successfully reproduced the experimental light path observed in the complicated photonic structure of the CLC droplet array more accurately than the analysis of CLC droplets by geometric optics with Bragg condition, and this method help us understand the polarization of the propagating light waves. The FDTD method holds great promise for the design of various photonic devices composed of curved photonic materials like CLC droplets and microcapsules.

  1. Optical and Physical Applications of Photocontrollable Materials: Azobenzene-Containing and Liquid Crystalline Polymers

    Directory of Open Access Journals (Sweden)

    Takashi Fukuda

    2012-01-01

    Full Text Available Photocontrol of molecular alignment is an exceptionally-intelligent and useful strategy. It enables us to control optical coefficients, peripheral molecular alignments, surface relief structure, and actuation of substances by means of photoirradiation. Azobenzene-containing polymers and functionalized liquid crystalline polymers are well-known photocontrollable materials. In this paper, we introduce recent applications of these materials in the fields of mechanics, self-organized structuring, mass transport, optics, and photonics. The concepts in each application are explained based on the mechanisms of photocontrol. The interesting natures of the photocontrollable materials and the conceptual applications will stimulate novel ideas for future research and development in this field.

  2. SYNTHESES AND CHARACTERIZATION OF A NEW TYPE OF LIQUID CRYSTALLINE POLYESTERS

    Institute of Scientific and Technical Information of China (English)

    BAI Ruke; WU Chengpei; ZOU Yingfeng; SUN Wu; PAN Caiyuan; Toshiyuki Uryu

    1994-01-01

    A new type of liquid crystalline polyesters with resorcin as one part of the mesogenic unit connected together by polymethylene, or phenylene group, and lateral groups consisting of a rigid azobenzene as another part of the mesogenic unit were synthesized by interfacial polymerization of diacyl chlorides in 1, 2-dichloroethane and 2,4-dihydroxy-4'-nitroazobenzene in aqueous alkaline solution. The polyester structures were confirmed by proton NMR and IR spectra. Their phase transition behavior and texture were studied by polarizing microscopy and DSC.

  3. Novel biphotonic holographic storage in a side-chain liquid crystalline polyester

    DEFF Research Database (Denmark)

    Ramanujam, P.S.; Hvilsted, S.; Andruzzi, F.

    1993-01-01

    We report novel biphotonic holographic storage of text and gratings on unoriented films of a side-chain liquid crystalline polyester capable of high density storage and complete erasure. The holograms have a typical size of 1 mm. The recording utilizes unusual photochemistry involving azo dye...... molecules. We believe that this technique would have a great potential in the recording of thousands of holograms in a two-dimensional plane, as for instance in text retrieval systems and in the fabrication of high density interconnects in optical neural networks....

  4. Electrically Conductive Compounds of Polycarbonate, Liquid Crystalline Polymer, and Multiwalled Carbon Nanotubes

    OpenAIRE

    Penwisa Pisitsak; Rathanawan Magaraphan; Sadhan C. Jana

    2012-01-01

    A thermotropic liquid crystalline polymer (LCP) was blended with polycarbonate (PC) and multiwalled carbon nanotube (CNT) with the goal of improving electrical conductivity and mechanical properties over PC. The LCP was anticipated to produce fibrillar domains in PC and help improve the mechanical properties. The study was carried out using two grades of LCP—Vectra A950 (VA950) and Vectra V400P (V400P). The compounds contained 20 wt% LCP and 0.5 to 15 wt% CNT. The compounds were prepared by m...

  5. Interferometric Sensor of Wavelength Detuning Using a Liquid Crystalline Polymer Waveplate

    Directory of Open Access Journals (Sweden)

    Paweł Wierzba

    2016-05-01

    Full Text Available Operation of a polarization interferometer for measurement of the wavelength changes of a tunable semiconductor laser was investigated. A λ/8 waveplate made from liquid crystalline polymer is placed in one of interferometers’ arms in order to generate two output signals in quadrature. Wavelength was measured with resolution of 2 pm in the wavelength range 628–635 nm. Drift of the interferometer, measured in the period of 500 s, was 8 nm, which corresponded to the change in the wavelength of 1.3 pm. If needed, wavelength-dependent Heydemann correction can be used to expand the range of operation of such interferometer.

  6. Interferometric Sensor of Wavelength Detuning Using a Liquid Crystalline Polymer Waveplate.

    Science.gov (United States)

    Wierzba, Paweł

    2016-01-01

    Operation of a polarization interferometer for measurement of the wavelength changes of a tunable semiconductor laser was investigated. A λ/8 waveplate made from liquid crystalline polymer is placed in one of interferometers' arms in order to generate two output signals in quadrature. Wavelength was measured with resolution of 2 pm in the wavelength range 628-635 nm. Drift of the interferometer, measured in the period of 500 s, was 8 nm, which corresponded to the change in the wavelength of 1.3 pm. If needed, wavelength-dependent Heydemann correction can be used to expand the range of operation of such interferometer. PMID:27171082

  7. Prediction and Observation of Sustained Oscillations in a Sheared Liquid Crystalline Polymer

    Science.gov (United States)

    Grosso, M.; Crescitelli, S.; Somma, E.; Vermant, J.; Moldenaers, P.; Maffettone, P. L.

    2003-03-01

    Experimental observations of sustained oscillations of both shear stress and first normal stress differences are reported in flowing liquid crystalline polymers in a limited range of shear rates. The results can be described by considering the response of a rigid-rod model. Depending on the initial conditions, the frequency spectrum of the stress signal contains either one or two characteristic frequencies. This can be explained by the occurrence of either pure “wagging” or the coexistence of wagging and “log-rolling” behavior of the director.

  8. A liquid-crystalline hexagonal columnar phase in highly-dilute suspensions of imogolite nanotubes

    Science.gov (United States)

    Paineau, Erwan; Krapf, Marie-Eve M.; Amara, Mohamed-Salah; Matskova, Natalia V.; Dozov, Ivan; Rouzière, Stéphan; Thill, Antoine; Launois, Pascale; Davidson, Patrick

    2016-01-01

    Liquid crystals have found wide applications in many fields ranging from detergents to information displays and they are also increasingly being used in the `bottom-up' self-assembly approach of material nano-structuration. Moreover, liquid-crystalline organizations are frequently observed by biologists. Here we show that one of the four major lyotropic liquid-crystal phases, the columnar one, is much more stable on dilution than reported so far in literature. Indeed, aqueous suspensions of imogolite nanotubes, at low ionic strength, display the columnar liquid-crystal phase at volume fractions as low as ~0.2%. Consequently, due to its low visco-elasticity, this columnar phase is easily aligned in an alternating current electric field, in contrast with usual columnar liquid-crystal phases. These findings should have important implications for the statistical physics of the suspensions of charged rods and could also be exploited in materials science to prepare ordered nanocomposites and in biophysics to better understand solutions of rod-like biopolymers.

  9. Ab initio calculations of the optical properties of crystalline and liquid InSb

    International Nuclear Information System (INIS)

    Ab initio calculations of the electronic and optical properties of InSb were performed for both the crystalline and liquid states. Two sets of atomic structure models for liquid InSb at 900 K were obtained by ab initio molecular dynamics simulations. To reduce the effect of structural peculiarities in the liquid models, an averaging of the two sets of the calculated electronic and optical properties corresponding to the two liquid models was performed. The calculated results indicate that, owing to the phase transition from crystal to liquid, the density of states around the Fermi level increases. As a result, the energy band gap opening near the Fermi level disappears. Consequently, the optical properties change from semiconductor to metallic behavior. Namely, owing to the melting of InSb, the interband transition peaks disappear and a Drude-like dispersion is observed in the optical dielectric functions. The optical absorption at a photon energy of 3.06 eV, which is used in Blu-ray Disc systems, increases owing to the melting of InSb. This increase in optical absorption is proposed to result from the increased optical transitions below 2 eV

  10. Characterization and in vitro permeation study of microemulsions and liquid crystalline systems containing the anticholinesterase alkaloidal extract from Tabernaemontana divaricata

    DEFF Research Database (Denmark)

    Chaiyana, Wantida; Rades, Thomas; Okonogi, Siriporn

    2013-01-01

    and water with the oil:surfactant ratios of 1:5 and 2:5. The formulations were characterized by photon correlation spectroscopy, polarizing light microscopy, differential scanning calorimetry, and viscosity measurement. A reverse micellar phase, w/o microemulsions, liquid crystalline systems, liquid...... crystal in microemulsion systems and coarse emulsions were formed along the aqueous dilution line of both oil:surfactant ratios. Formulations with the ratio of 1:5 containing 0.1μg/ml extract showed a significantly higher acetylcholinesterase inhibition than those with the ratio of 2:5. The skin of...... stillborn piglet was used in the permeation study. The liquid crystalline and microemulsion systems significantly increased the transdermal delivery of the extract within 24h. It was concluded that the alkaloidal extract from T. divaricata stem loaded in liquid crystalline or microemulsion systems...

  11. Observation of the structure and the deformation of a liquid-crystalline polymer under shear flow

    International Nuclear Information System (INIS)

    We determined the evolution of the main-chain conformation and of the liquid crystalline structure of a liquid crystal poly-methacrylate in the smectic phase, versus shear rate. It is shown that the macroscopic shear was transmitted to the smectic layers which ensured an efficient shear of the polymer main-chains. The outcome was a macroscopic orientation of the smectic mono-domains with the smectic planes parallel to the shear plane. The polymer main-chains already confined by the mesogenic layers, were in addition, the more elongated along the velocity direction that the stronger, the shear was. These results were obtained in situ by the observations in the shear plane and in the vorticity plane. (authors)

  12. MORPHOLOGY STUDY OF A SERIES OF AZOBENZENE-CONTAINING SIDE-ON LIQUID CRYSTALLINE TRIBLOCK COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    Wei Deng; Annie Br(u)let; Pierre-antoine Albouy; Patrick Keller; Xiao-gong Wang; Min-hui Li

    2012-01-01

    A series of azobenzene containing side-on liquid crystalline ABA triblock copolymers were investigated.This triblock series possesses the same central liquid crystal block B and various lengths of the amorphous block A.Transmission electron microscopy (TEM),small angle X-rays and neutron scattering (SAXS and SANS) were used to study their morphologies.Aider annealing the samples over weeks at a temperature within the nematic temperature range of block B,different morphologies (disordered,lamellar,perforated layer and hexagonal cylinder) were observed by TEM.The alignment behavior of these azo triblock copolymers in the magnetic field for artificial muscle application,as well as the phase period and the order-disorder transition (ODT) were studied in situ by SANS.

  13. Polarized Emission of Wholly Aromatic Bio-Based Copolyesters of a Liquid Crystalline Nature

    Directory of Open Access Journals (Sweden)

    Daisaku Kaneko

    2011-05-01

    Full Text Available A novel thermotropic liquid crystalline polymers poly{3-benzylidene amino-4-hydroxybenzoic acid (3,4-BAHBA-co-trans-4-hydroxycinnamic acid (4HCA: trans-coumaric acid} (Poly(3,4-BAHBA-co-4HCA, was synthesized by the thermal polycondensation of 4HCA and 3,4-BAHBA, which was synthesized by a reaction of 3-amino-4-hydroxybenzoic acid (3,4-AHBA with benzaldehyde. When the 4HCA compositions of Poly(3,4-BAHBA-co-4HCAs were above 55 mol%, the copolymers showed a nematic, liquid crystalline phase. Differential scanning calorimetry (DSC measurements of the copolymers showed a high glass transition temperature of more than 100 °C, sufficient for use in engineering plastics. Furthermore, the copolymers showed photoluminescence in an N-methylpyrrolidone (NMP solution under ultraviolet (UV light with a wavelength of 365 nm. Oriented film of Poly(3,4-BAHBA-co-4HCA with a 4HCA composition of 75 mol% emitted polarized light, which was confirmed by fluorescent spectroscopy equipped with parallel and crossed polarizers.

  14. Surface and liquid-crystalline properties of FmHnFm triblock semifluorinated n-alkanes.

    Science.gov (United States)

    Chachaj-Brekiesz, Anna; Górska, Natalia; Osiecka, Natalia; Makyła-Juzak, Katarzyna; Dynarowicz-Łątka, Patrycja

    2016-05-01

    A series of triblock semifluorinated n-alkanes of the general formula: F(CF2)m(CH2)n(CF2)mF, (in short FmHnFm), where m=10, 12, and n=6, 8, and 12 have been synthesized and employed for liquid crystalline studies and Langmuir monolayer characterization. Differential scanning calorimetry (DSC) measurements together with texture observation with polarizing microscope (POM) revealed the presence of liquid crystalline smectic phases for all the investigated homologs. The behavior of the studied molecules spread at the free water surface has also been investigated. Our results show for the first time that these unusual film-forming materials, which are completely hydrophobic in nature and do not possess any polar group in their structure, are surface active and form insoluble (Langmuir) monolayers at the air/water interface. Due to the fact that these molecules are chemically inert and, similar to the semifluorinated diblocks, are not toxic, they may be destined for biomedical uses as gas carriers and contrast agents, as well as in drug delivery systems. PMID:26952494

  15. Electrochemical studies of redox probes in self-organized lyotropic liquid crystalline systems

    Indian Academy of Sciences (India)

    P Suresh Kumar; V Lakshminarayanan

    2009-09-01

    Lyotropic liquid crystalline phases formed by surfactants are of special importance due to their close resemblance to biological systems. The redox reactions in such ordered media are of fundamental interest in understanding several complex processes occurring in the biological media, where the former can act as model systems. In this work, we have carried out the redox reactions of benzoquinone| hydroquinone, methyl viologen and ferrocenemethanol probes in a lyotropic hexagonal columnar phase (H1 phase) using cyclic voltammetry and electrochemical impedance spectroscopic studies. The liquid crystalline phase we have studied is made up of the non-ionic surfactant, Triton X-100 and water. Polarizing optical microscopic examination confirmed that the columnar hexagonal phase is retained even after the addition of redox probe as well as the supporting electrolyte. Our studies show a significant shift in the half-peak potentials of the redox probes in the H1 phase as compared to the solvent phase. The diffusion coefficient values for different redox probes in the H1 phase were also found to be significantly reduced when compared to the corresponding solvent media.

  16. Polarization-Sensitive Two-Photon Microscopy Study of the Organization of Liquid-Crystalline DNA

    Science.gov (United States)

    Mojzisova, Halina; Olesiak, Joanna; Zielinski, Marcin; Matczyszyn, Katarzyna; Chauvat, Dominique; Zyss, Joseph

    2009-01-01

    Abstract Highly concentrated DNA solutions exhibit self-ordering properties such as the generation of liquid-crystalline phases. Such organized domains may play an important role in the global chromatin topology but can also be used as a simple model for the study of more complex 3D DNA structures. In this work, using polarized two-photon fluorescence microscopy, we report on the orientation of DNA molecules in liquid-crystalline phases. For this purpose, we analyze the signal emitted by fluorophores that are noncovalently bound to DNA strands. In nonlinear processes, excitation occurs exclusively in the focal volume, which offers advantages such as the reduction of photobleaching of out-of-focus molecules and intrinsic 3D sectioning capability. Propidium iodide and Hoechst, two fluorophores with different DNA binding modes, have been considered. Polarimetric measurements show that the dyes follow the alignment with respect to the DNA strands and allow the determination of the angles between the emission dipoles and the longitudinal axis of the DNA double strand. These results provide a useful starting point toward the application of two-photon polarimetry techniques to determine the local orientation of condensed DNA in physiological conditions. PMID:19843467

  17. Thermomyces lanuginosus lipase-catalyzed hydrolysis of the lipid cubic liquid crystalline nanoparticles.

    Science.gov (United States)

    Barauskas, Justas; Anderberg, Hanna; Svendsen, Allan; Nylander, Tommy

    2016-01-01

    In this study well-ordered glycerol monooleate (GMO)-based cubic liquid crystalline nanoparticles (LCNPs) have been used as substrates for Thermomyces lanuginosus lipase in order to establish the relation between the catalytic activity, measured by pH-stat titration, and the change in morphology and nanostructure determined by cryogenic transmission electron microscopy and synchrotron small angle X-ray diffraction. The initial lipase catalyzed LCNP hydrolysis rate is approximately 25% higher for large 350nm nanoparticles compared to the small 190nm particles, which is attributed to the increased number of structural defects on the particle surface. At pH 8.0 and 8.4 bicontinuous Im3m cubic LCNPs transform into "sponge"-like assemblies and disordered multilamellar onion-like structures upon exposure to lipase. At pH 6.5 and 7.5 lipolysis induced phase transitions of the inner core of the particles, following the sequence Im3m cubic → reversed hexagonal → reversed micellar Fd3m cubic → reversed micelles. These transitions to the liquid crystalline phases with higher negative curvature of the lipid/water interface were found to trigger protonation of the oleic acid produced during lipase catalyzed reaction. The increase curvature of the reversed discrete micellar cubic phase was suggested to cause an increase in the oleic acid pKa to a larger value observed by pH-stat titration. PMID:26047576

  18. Theory of microphase separation on side-chain liquid-crystalline polymers with flexible spacers.

    Science.gov (United States)

    Hernández-Jiménez, M; Westfahl, H

    2007-05-01

    We model a melt of monodisperse side-chain liquid-crystalline polymers as a melt of comb copolymers in which the side groups are rod-coil diblock copolymers. We consider both excluded-volume and Maier-Saupe interactions. The first acts among any pair of segments while the latter acts only between rods. Using a free-energy functional calculated from this microscopic model, we study the spinodal stability of the isotropic phase against density and orientational fluctuations. The phase diagram obtained in this way predicts nematic and smectic instabilities as well as the existence of microphases or phases with modulated wave vector but without nematic ordering. Such microphases are the result of the competition between the incompatibility among the blocks and the connectivity constraints imposed by the spacer and the backbone. Also the effects of the polymerization degree and structural conformation of the monomeric units on the phase behavior of the side-chain liquid-crystalline polymers are studied. PMID:17541501

  19. PREPARATION AND CHARACTERIZATION OF SHISH-KEBAB TYPE LIQUID CRYSTALLINE POLY(p-PHENYLENEVINYLENE)

    Institute of Scientific and Technical Information of China (English)

    Shi-jun Zheng; Kazuo Akagi; Qun Xu; Shao-kui Cao; Qi-feng Zhou

    2006-01-01

    Novel shish-kebab type liquid crystalline poly(p-phenylenevinylene) derivatives were synthesized by Stille coupling reaction from 2,5-bis[(4-n-alkoxyl)benzoyloxy]1,4-dibromobenzene (monomer 1) and 1,2-bis(tributylstannyl)ethylene (monomer 2). The polymers with alkoxy groups are soluble in common organic solvents and exhibit blue fluorescence. Both the cast film and the annealed film have large red-shifts in fluorescence spectra and show yellow fluorescence. The polymers with CN and NO2 groups show poor solubility and green fluorescence. All the polymers possess liquid crystalline smectic phases. The melting point (Tm) of the polymers decreases when the length of the alkoxy tails of the mesogenic units increases. The polymers are easily aligned under a magnetic field of 10 Tesla. It is found that the conjugated backbone and LC side chain are aligned perpendicular and parallel to the magnetic field, respectively. The polymers show optical dichroism in fluorescence spectra, suggesting that they are available for advance materials with linear optical polarization.

  20. The Effect of Liquid Crystalline Structures on Antiseizure Properties of Aqueous Solutions of Ethoxylated Alcohols

    Directory of Open Access Journals (Sweden)

    Anna Bak

    2010-01-01

    Full Text Available Aqueous solutions of ethoxylated alcohols which form lyotropic liquid crystals at high concentrations (40–80% were selected as model lubricating substances. Microscopic studies under polarized light and viscosity measurements were carried out in order to confirm the presence of liquid crystalline structures in the case of alcohol solutions with ethoxylation degrees of 3, 5, 7 and 10. Microscopic images and viscosity coefficient values characteristic of various mesophases were obtained. As expected, the viscosity of LLCs decreases considerably with an increase in shearing rate which is characteristic of liquid crystals being non-Newtonian liquids. Antiseizure properties were determined by means of a four-ball machine (T-02 Tester and characterized by scuffing load (Pt, seizure load (Poz and limiting pressure of seizure (poz. Alcohol ethoxylates forming mesophases in aqueous solutions have the strongest effect on the Pt values which are several times higher than those measured in the presence of water. Ethoxylates with higher degrees of ethoxylation exhibit higher values of scuffing load. Those changes have been interpreted as a result of higher cloud points at which those compounds lose their amphiphilic properties. In general, the presence of mesophases in the bulk phase and particularly in the surface phase may lead to the formation of a lubricant film which separates the frictionally cooperating elements of a friction pair. The antiseizure efficiency of alcohol solutions is highest up to the load value which does not exceed the scuffing load value.

  1. Silica nanoparticle stabilization of liquid crystalline lipid dispersions: impact on enzymatic digestion and drug solubilization.

    Science.gov (United States)

    Bhatt, Achal B; Barnes, Timothy J; Prestidge, Clive A

    2015-01-01

    The high internal surface area and drug solubilizing capacity of liquid crystal lipids makes them promising oral drug delivery systems. Pluronic F127 is typically used to disperse highly viscous cubic liquid crystal lipids into cubosomes; however, such copolymers alter the internal structure and provide little control over enzymatic digestion. This study aimed to use hydrophilic silica nanoparticles to stabilize glyceryl monooleate (GMO) cubosomes prepared by ultrasonication. We investigate the influence of silica nanoparticles size and concentration on the physical (colloidal) and chemical (enzymatic digestion) stability, as well as in vitro solubilization of cinnarizine as a poorly soluble model drug. Silica stabilized nanostructured liquid crystal dispersions (120 nm to150 nm in diameter and zeta potentials of-30 mV to -60 mV) were successfully prepared with excellent long-term stability (Silica stabilized GMO cubosomes demonstrated reduced enzymatic digestion compared to pluronic F127 stabilized cubosomes. This reduced digestion was attributed to a combination of adsorbed silica nanoparticles acting as a physical barrier and excess dispersed silica adsorbing/scavenging the lipase enzyme. Under simulated intestinal digestion conditions, silica stabilized GMO cubosomes showed a greater solubilization capacity for cinnarizine, which precipitated in non-crystalline form, in comparison to pure drug suspensions or pluronic F127 stabilized GMO cubosomes. Silica nanoparticle stabilized GMO liquid crystal dispersions are a promising oral delivery vehicle. PMID:25176029

  2. Synthesis and characterization of thermotropic liquid crystalline polyester/multi-walled carbon nanotube nanocomposites

    International Nuclear Information System (INIS)

    Thermotropic liquid crystalline polyester (TLCP) was synthesized via low-temperature solution polycondensation from 1,4-Bis(4-Hydroxybenzoyloxy)butane and terephthaloyl dichloride. Polymer nanocomposites based on a small quantity of multi-walled carbon nanotubes (MWNTs) were prepared by in situ polymerization method. The wide-angle X-ray diffraction (WAXD) results suggested that the addition of MWNTs to TLCP matrix did not significantly change the crystal structure of TLCP. The interactions between the molecules of the TLCP host phase and the carbon nanotubes were investigated through Raman spectroscopy investigations. We detected a distinct wave number shift of the radial breathing modes, confirming the carbon nanotubes interacted with the surrounding liquid crystal molecules, most likely through aromatic interactions (π-stacking). The interactions between liquid crystal host and nanotube guests were also evident from a polarizing microscopy (POM) study of the liquid crystal-isotropic phase transition in the proximity of nanotubes. The thermal properties and the morphological properties of the TLCP/MWNTs nanocomposites were investigated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). TGA data demonstrated the addition of a small amount of MWNTs into TLCP matrix could improve the thermal stability of TLCP matrix. DSC results revealed that melt transition temperatures and isotropic transition temperatures of the hybrids were enhanced.

  3. Síntese de copolímeros em bloco com propriedades líquido cristalinas Synthesis of liquid crystalline block copolymers

    OpenAIRE

    Maria Rita Guinancio Coelho; Ailton de Souza Gomes

    2007-01-01

    The principal techniques for the synthesis of liquid crystalline block copolymers are reviewed. The syntheses are done by living/controlled free radical chain polymerization. The copolymers display an amorphous continuous phase and a discontinuous liquid crystalline phase (LC). The presence of oxypropylenic segments disturbs the range of mesophase transitions at lower temperatures. This behavior is not observed when styrenic segments are employed and suggests that the liquid crystalline behav...

  4. Relaxation process and phase transition of lanthanide liquid crystalline complexes by photoacoustic spectroscopy

    Institute of Scientific and Technical Information of China (English)

    LI Junjia; YANG Yuetao; LIU Xiaojun; ZHANG Shuyi; ZHANG Zhongning

    2008-01-01

    Lanthanide-containing liquid crystals exhibiting smectic A phase close to room temperature were obtained. Photoacoustic (PA) spectroscopy was used to study the spectral properties and phase transitions of liquid crystalline metal complexes. It was found that PA intensity of the ligand had a relationship with the probability of nonradiative transitions, which increased in the order of Eu(tta)3L2liquid crystals containing metal ions.

  5. RHEOLOGICAL PROPERTIES OF LIQUID CRYSTALLINE COPOLY (p-HYDROXYBENZOATE/BISPHENOL A TEREPHTHALATE)

    Institute of Scientific and Technical Information of China (English)

    WANG Yong; WU Dacheng; LI Ruixia

    1996-01-01

    Various aspects of the rheological behaviour of liquid crystalline copolyesters, i.e.,samples of copoly (p-hydroxybenzoate/bisphenol A terephthalate), were explored by using Instron capillary rheometer. The experimental results indicated that the apparent viscosity was affected significantly by shear rate, melt temperature and p-hydroxybenzoate unit content. The flow activation energies △Eη are in the range of 205.1 to 74.5 k J/mol, depending on the shear rate of 10-1000 s-1, at temperature 568-603K. These copolyesters exhibit a yield phenomenon in the shear flow, and the values of yield stress decrease with increasing temperature. It is quite unusual that the extrudate of the copolyester shows the smaller swelling ratio even than unity at the lower temperature and lower shear rates.

  6. Synthesis, characterization, and rheology of functional and heterocyclic liquid crystalline polymers

    Science.gov (United States)

    Huang, Wenyi

    Three segmented main-chain thermotropic liquid crystalline polymers (TLCPs) functionalized with nitrogen-containing heterocyclic groups were synthesized; namely PyHQ12 having pendent pyridyl group, PABP having side-chain azopyridyl group with flexible spacer, and PTBP containing side-chain terpyridine group with flexible spacer. The principles of specific interactions were applied to prepare supramolecular structures and organoclay or clay nanocomposites based on these functional TLCPs. Three combined main-chain/side-chain liquid-crystalline polymers (MCSCLCPs) were prepared via hydrogen bonding or ionic interactions based on PyHQ12 and PABP. The presence of hydrogen bonds in self-assembled PyHQ12-7CNCOOH and PABP-AA, and the presence of ionic interactions in self-assembled PABP-TSA, which exist above their respective clearing temperatures, were confirmed using Fourier transform infrared (FTIR) spectroscopy, the thermal transitions in each MCSCLCP were determined using differential scanning calorimetry (DSC), and the mesophase structures of each self-assembled MCSCLCP were characterized using polarized optical microscopy (POM) and wide-angle X-ray diffraction (WAXD). PyHQ12 was observed to be very effective in exfoliating organoclay (Cloisite 30B) aggregates, because of the formation of hydrogen bonds, as determined by in situ FTIR spectroscopy, between the pendent pyridyl group in PyHQ12 and the hydroxyl groups in the surfactant MT2EtOH residing at the surface of Cloisite 30B. Thus, functionality in TLCP is necessary to obtain highly dispersed organoclay nanocomposites, but at the same time there is a possibility to lose some degree of liquid crystallinity in the TLCP, due to the proximity of the pendent pyridyl group to the mesogenic main-chain backbone. Thus, another functional TLCP, PABP having side-chain azopyridyl group with flexible spacer, was synthesized. It has been found that the liquid crystallinity of PABP in the organoclay nanocomposites was more or

  7. Nanorods in functionalized block-copolymer gels: Flexible ladders and liquid crystalline order in curved geometries

    Science.gov (United States)

    Knorowski, C.; Travesset, A.

    2012-12-01

    Polymer nanocomposites (PNCs) hold great promise for designing novel materials. Current challenges in PNCs are achieving nanosized dispersion of the inorganic component as well as robust control of nanoparticle orientation. We show that a gel of multi-block polymers with functionalized end groups that have specific affinity towards nanorods provides a general example of a PNC where the inorganic component is dispersed at the nanometer scale and displays long range as well as orientation order. We find a novel type of liquid crystalline (LC) order consisting of thin nanorod strips, i.e., “flexible ladders” (FL). Depending on concentration and affinity, FL display positional long-range order and patch together into 2D smectic phases. We discuss implications for designing new PNCs and address possible realizations of our systems via DNA linkers. The problem of LC order on curved geometries is also discussed.

  8. The influence of intraannular templates on the liquid crystallinity of shape-persistent macrocycles

    Directory of Open Access Journals (Sweden)

    Joscha Vollmeyer

    2014-04-01

    Full Text Available A series of shape-persistent phenylene–ethynylene–naphthylene–butadiynylene macrocycles with different extraannular alkyl groups and intraannular bridges is synthesized by oxidative Glaser-coupling of the appropriate precursors. The intraannular bridges serve in this case as templates that reduce the oligomerization even when the reaction is not performed under pseudo high-dilution conditions. The extraannular as well as the intraannular substituents have a strong influence on the thermal behavior of the compounds. With branched alkyl chains at the periphery, the macrocycles exhibit liquid crystalline (lc phases when the interior is empty or when the length of the alkyl bridge is just right to cross the ring. With a longer alkyl or an oligoethylene oxide bridge no lc phase is observed, most probably because the mesogene is no longer planar.

  9. CHOLESTERIC LIQUID CRYSTALLINE CHARACTER ON THE SURFACE OF CHITOSAN/POLYACRYLIC ACID COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    Yan-ming Dong; Yu-song; Wu Mian Wang

    2001-01-01

    The cholesteric liquid crystalline structure in chitosan/polyacrylic acid composite films was studied by surface techniques. A periodical lamellar-like structure was observed in the permanganic acid etched film surface by both scanning electron microscopy (SEM) and atomic force microscopy (AFM), instead of the thumb-print texture which can be detected with polarized optical microscopy. It is suggested that the periodical lamellar-like structure is induced by the etching selectivity between cholesteric layers due to different molecular arrangement on the film surface. Four kinds of perpendicular disclinations, I.e. Χ→τ- + λ+, χ→λ- + τ+, χ→τ- + τ+ and χ→λ- + λ+, were found in the composite films from SEM observations. The smallest periodicity of lamellar-like structure (equals to halfpitch) is 20~40 nm measured with AFM.

  10. Photomobile polymer materials with crosslinked liquid-crystalline structures: molecular design, fabrication, and functions.

    Science.gov (United States)

    Ube, Toru; Ikeda, Tomiki

    2014-09-22

    Crosslinked liquid-crystalline polymer materials that macroscopically deform when irradiated with light have been extensively studied in the past decade because of their potential in various applications, such as microactuators and microfluidic devices. The basic motions of these materials are contraction-expansion and bending-unbending, which are observed mainly in polysiloxanes and polyacrylates that contain photochromic moieties. Other sophisticated motions such as twisting, oscillation, rotation, and translational motion have also been achieved. In recent years, efforts have been made to improve the photoresponsive and mechanical properties of this novel class of materials through the modification of molecular structures, development of new fabrication methods, and construction of composite structures. Herein, we review structures, functions, and working mechanisms of photomobile materials and recent advances in this field. PMID:25196371

  11. Elementary statistical models for nematic transitions in liquid-crystalline systems

    Science.gov (United States)

    Liarte, Danilo B.; Salinas, Silvio R.

    2014-03-01

    We introduce a simple Maier-Saupe-Zwanzig (MSZ) model to describe the well-known first-order nematic-isotropic transition in liquid-crystalline systems. We then use the MSZ model, with the addition of disorder degrees of freedom, to investigate the stability of a biaxial nematic phase in a mixture of rods and disks. There is a biaxial nematic structure if we consider a fixed distribution of rods and disks. For a thermalized distribution of shapes, however, this biaxial structure becomes thermodynamically unstable. We then resort to a formalism that accounts for two sets of relaxation times, and show that a small departure from complete thermalization is enough to recover a stable biaxial structure. As another application of the MSZ model, we report an investigation of some properties of nematic elastomers. We point out the possibility of continuous nematic transitions, and reproduce a characteristic stress-strain response, with a plateau that indicates a polydomain-monodomain transition.

  12. LIQUID CRYSTALLINE BEHAVIOR OF HYDROXYPROPYL CELLULOSE ESTERIFIED WITH 4-ALKOXYBENZOIC ACID.

    Directory of Open Access Journals (Sweden)

    Yehia Fahmy

    2010-07-01

    Full Text Available A series of 4- alkyoxybenzoyloxypropyl cellulose (ABPC-n samples was synthesized via the esterification of hydroxypropyl cellulose (HPC with 4-alkoxybenzoic acid bearing different numbers of carbon atoms. The molecular structure of the ABPC-n was confirmed by Fourier transform infrared (FT-IR spectroscopy and 1H NMR spectroscopy. The liquid crystalline (LC phases and transitions behaviors were investigated using differential scanning calorimetry (DSC, polarized light microscopy (PLM, and refractometry. It was found that the glass transition (Tg and clearing (Tc temperatures decrease with increase of the alkoxy chain length. It was observed that the derivatives with an odd number of carbon atoms are non-mesomorphic. This series of ABPC-n polymers exhibit characteristic features of cholesteric LC phases between their glass transition and isotropization temperatures.

  13. Structural Formation Process of Microphase Separated Films with Liquid Crystalline Phase Transition

    Science.gov (United States)

    Komura, Motonori; Iyoda, Tomokazu

    2008-03-01

    Ordered nanostructures arising from the microphase separation of block copolymers have driven one to fabricate nanofunctional materials as fundamental technology of the coming electronic and photonic materials. Thin films of a series of newly designed amphiphilic block copolymer consisting of hydrophilic polyethylene oxide (PEO) and hydrophobic polymethacrylate with azobenzene-mesogen in side-chain (PMA(Az)) show highly ordered microphase separation with PEO cylinders perpendicularly oriented to the film surface. In the present report, we investigated a structural formation process of the microphase separated films by temperature controlled atomic force microscopy (AFM) and grazing incidence small angle X-ray scattering (GISAXS). These measurements revealed that homeotropic alignments of Az liquid crystalline layers predominated the cylinder orientation, which corresponded to a direction of body centered cubic structure under annealing condition, in disagreement with cylinder orientation of order-order transition of traditional block copolymers.

  14. Ordering and dewetting in spin-coated films of a liquid crystalline main chain polymer

    International Nuclear Information System (INIS)

    The ordering of spin-coated films of a main-chain smectic liquid crystalline polymer with an azobenzene group connected by flexible spacers to a phenyl malonate unit has been studied as a function of film thickness using scanning force microscopy and UV/Vis spectroscopy. Already the as-prepared films are characterized by a significant out-of-plane orientation of the azobenzene groups. Annealing of films thicker than 7 nm results in aggregation and homeotropical alignment of azobenzene groups forming smectic layers parallel to the substrate. An optically isotropic mesophase was found upon annealing in the temperature range of smectic mesophase. Films thinner than the bilayer thickness of 7 nm exhibit a completely different behavior, whereby spin-coating results in a spontaneously homeotropic alignment of the azobenzene units. A subsequent annealing generates a structure of holes and rims. Within the holes a polymer monolayer remains, planarly aligned to substrate

  15. Kinetic theory for flows of nonhomogeneous rodlike liquid crystalline polymers with a nonlocal intermolecular potential.

    Science.gov (United States)

    Wang, Qi; E, Weinan; Liu, Chun; Zhang, Pingwen

    2002-05-01

    The Doi kinetic theory for flows of homogeneous, rodlike liquid crystalline polymers (LCPs) is extended to model flows of nonhomogeneous, rodlike LCPs through a nonlocal (long-range) intermolecular potential. The theory features (i) a nonlocal, anisotropic, effective intermolecular potential in an integral form that is consistent with the chemical potential, (ii) short-range elasticity as well as long-range isotropic and anisotropic elasticity, (iii) a closed-form stress expression accounting for the nonlocal molecular interaction, and (iv) an extra elastic body force exclusively associated with the integral form of the intermolecular potential. With the effective intermolecular potential, the theory is proven to be well posed in that it warrants a positive entropy production and thereby the second law of thermodynamics. Approximate theories are obtained by gradient expansions of the number density function in the free energy density. PMID:12059561

  16. Pendant triazole ring assisted mesogen containing side chain liquid crystalline polymethacrylates: Synthesis and characterization

    Indian Academy of Sciences (India)

    T Palani; C Saravanan; P Kannan

    2011-01-01

    Two series of click chemistry assisted alkoxymethyl-1H-[1,2,3]-triazol-1-yl containing sidechain liquid-crystalline polymethacrylates were synthesized by free radical polymerization technique. Mesogen was linked to backbone through various spacer units. Monomers and polymers were characterized by FT-IR, 1H and 13C-NMR spectral techniques. Thermal stability of polymers was confirmed by thermogravimetric analysis. Mesomorphic property and phase transition temperature of polymers were analysed by differential scanning calorimetry and polarized optical microscopy. Phase transition temperature and mesomorphic property of polymers with respect to insertion of polar alkoxy group on terminal triazole ring and spacer length between backbone and mesogen were investigated. Polymers exhibited grainy like textures under polarized optical microscopy. Spacer length between mesogen and backbone alters phase transition temperature of the polymers.

  17. New theory for competing interactions and microstructures in partially-ordered (liquid-crystalline) phases

    International Nuclear Information System (INIS)

    A summary of results from a unique statistical-physics theory to predict and explain competing interactions and resulting microstructures in some partially-ordered [in this case, liquid-crystalline (LC)] phases is presented. The static aspects of both partial orientational and partial positional ordering of the molecules into various microstructures in these phases (including the incommensurate smectic-Ad phase) can be understood in terms of various competing interactions (both entropic and energetic) involved in the packing together of the different molecular sub-units at given pressures and temperatures. These microstructures are predicted and explained (using no ad hoc or arbitrarily adjustable parameter) as a function of molecule chemical structure [including lengths and shapes (from bond lengths and angles), intramolecular rotations, site-site polarizabilities and pair potentials, dipole moments, etc]. Theoretical results are presented for the nematic, re-entrant nematic, smectic-Ad, and smectic-Al LC phases and the isotropic phase

  18. Novel side-chain liquid crystalline polyester architecture for reversible optical storage

    DEFF Research Database (Denmark)

    Hvilsted, Søren; Andruzzi, Fulvio; Kulinna, Chrisian;

    1995-01-01

    New side-chain liquid crystalline polyesters have been prepared by melt transesterification of diphenyl tetradecanedioate and a series of mesogenic 2-[omega-[4-[(4-cyanophenyl)azo]phenoxyl] alkyl]-1,3-propanediols, where the alkyl spacer is hexa-, octa-, and decamethylene in turn. The polyesters...... have molecular masses in the range 5000-89 000. Solution C-13 NMR spectroscopy has been employed to identify carbons of polyester repeat units and of both types of end groups. Polyester phases and phase transitions have been investigated in detail by polarizing optical microscopy and differential...... scanning calorimetry for the hexamethylene spacer architecture with different molecular masses. Using FTIR polarization spectroscopy, the segmental orientation in unoriented polyester films induced by argon ion laser irradiation has been followed and an irradiation-dependent order parameter for the...

  19. High diffraction efficiency polarization gratings recorded by biphotonic holography in an azobenzene liquid crystalline polyester

    International Nuclear Information System (INIS)

    High diffraction efficiencies have been achieved with polarization gratings recorded in thin films of an azobenzene side-chain liquid crystalline polyester by means of biphotonic processes. Efficiency values up to 30% have been reached after an induction period of 300 s and subsequent evolution with the sample in darkness. These values are at least two orders of magnitude higher than those previously reported for biphotonic recording. The gratings can be erased with unpolarized blue light and partial recovery of the diffraction efficiency has been observed after the erasure process when the sample is kept in darkness. Red light illumination of the erased film increases the recovered efficiency value and the recovery rate. [copyright] 2001 American Institute of Physics

  20. Flow Induced Structures in Liquid Crystalline Polymers as Studied by Neutron Scattering

    Science.gov (United States)

    Dadmun, Mark

    2000-03-01

    Small angle neutron scattering has been utilized to examine the orientation of liquid crystalline polymer systems during and after the application of a flow field. Thermotropic systems show unique behavior including perpendicular orientation to the flow direction at low temperature and a temperature dependence of the molecular orientation within in the nematic regime. It is also found that the orientation is long-lived after the removal of the shear field in the thermotropic system. In lyotropic systems, however, an interesting dependence on solvent is found. The alignment behavior of poly(benzyl L-glutamate) (PBLG) in deuterated benzyl alcohol (DBA) differs significantly from the alignment of PBLG in deuterated m-cresol (DMC) during shear and upon shear cessation. This is unexpected, as DMC is an isomer of DBA. Possible explanations for this behavior will be discussed.

  1. Self-aggregation and liquid crystalline behavior of new ester-functionalized quinuclidinolium surfactants.

    Science.gov (United States)

    Bhadani, Avinash; Endo, Takeshi; Koura, Setsuko; Sakai, Kenichi; Abe, Masahiko; Sakai, Hideki

    2014-08-01

    A new type of ester-based cationic surfactant having a quinuclidinolium headgroup has been synthesized starting from linear fatty alcohols and has been characterized using spectroscopic techniques. The self-aggregation and thermodynamic properties of these surfactants have been investigated by pendant-drop surface tensiometry and conductivity measurements. The liquid crystalline behaviors of these surfactants were investigated by small-angle X-ray scattering (SAXS) technique. The quinuclidinolium headgroup demonstrated a unique ability to interlock among themselves thus affecting the physicochemical properties of surfactants in aqueous solution. The current research finding supports the new concept of headgroup interlocking which is supported by 1D and 2D NMR studies. PMID:25058797

  2. Lyotropic Liquid Crystalline Cubic Phases as Versatile Host Matrices for Membrane-Bound Enzymes.

    Science.gov (United States)

    Sun, Wenjie; Vallooran, Jijo J; Fong, Wye-Khay; Mezzenga, Raffaele

    2016-04-21

    Lyotropic liquid crystalline cubic mesophases can function as host matrices for enzymes because of their biomimetic structural characteristics, optical transparency, and capability to coexist with water. This study demonstrates that the in meso immobilized membrane-bound enzyme d-fructose dehydrogenase (FDH) preserves its full activity, follows ideal Michaelis-Menten kinetics, and shows improved stability compared to its behavior in solution. Even after 5 days, the immobilized FDH retained its full activity in meso, whereas a model hydrophilic enzyme, horseradish peroxidase, maintained only 21% of its original activity. We reason that the lipidic bilayers in the three-dimensional structures of cubic mesophases provide an ideal environment for the reconstitution of a membrane-bound enzyme. The preserved activity, long-term stability, and reusability demonstrate that these hybrid nanomaterials are ideal matrices for biosensing and biocatalytic fuel cell applications. PMID:27050734

  3. Self-assembled liquid-crystalline folate nanoparticles for in vitro controlled release of doxorubicin.

    Science.gov (United States)

    Misra, Rahul; Mohanty, Sanat

    2015-02-01

    Liquid-crystalline folate nanoparticles are ordered in structure which offers several advantages like high encapsulation of drugs, controlled release rates, biocompatible in nature. Moreover, it facilitates the cellular uptake of nanodrugs without any extra step of folate ligand based targeting. The size of these nanocarriers as well as the release profiles of drugs from these nano-carriers can be controlled precisely. Folate molecules self-assemble in ordered stacks and columns even at low concentration of 0.1wt%. Doxorubicin molecules get intercalated within the folate stacks and are developed into nanoparticles. These nanoparticles are composed of highly ordered folate self-assembly which encapsulate doxorubicin molecules. These drug molecules can be released in a controlled manner by disrupting this assembly in the environment of monovalent cations. The ordered structure of folate nanoparticles offers low drug losses of about 4-5%, which is significant in itself. This study reports the size-control method of forming doxorubicin encapsulated folate nanoparticles as well as the parameters to control the release rates of doxorubicin through liquid-crystalline folate nanoparticles. It has been demonstrated that doxorubicin release rates can be controlled by controlling the size of the nanoparticles, cross-linking cation and cross-linking concentration. The effect of different factors like drug loading, release medium, and pH of the medium on doxorubicin release rates was also studied. Moreover, this study also addresses the comparative in vitro cytotoxic performance of Doxorubicin loaded folate nanoparticles and cellular uptake of nano-carriers on cancer and normal cell line. PMID:25661378

  4. Local order and orientational correlations in liquid and crystalline phases of carbon tetrabromide from neutron powder diffraction measurements

    CERN Document Server

    Temleitner, László

    2010-01-01

    The liquid, plastic crystalline and ordered crystalline phases of CBr$_4$ were studied using neutron powder diffraction. The measured total scattering differential cross-sections were modelled by Reverse Monte Carlo simulation techniques (RMC++ and RMCPOW). Following successful simulations, the single crystal diffraction pattern of the plastic phase, as well as partial radial distribution functions and orientational correlations for all the three phases have been calculated from the atomic coordinates ('particle configurations'). The single crystal pattern, calculated from a configuration that had been obtained from modelling the powder pattern, shows identical behavior to the recent single crystal data of Folmer et al. (Phys. Rev. {\\bf B77}, 144205 (2008)). The BrBr partial radial distribution functions of the liquid and plastic crystalline phases are almost the same, while CC correlations clearly display long range ordering in the latter phase. Orientational correlations also suggest strong similarities bet...

  5. Evaluation of Microemulsion and Lamellar Liquid Crystalline Systems for Transdermal Zidovudine Delivery.

    Science.gov (United States)

    Carvalho, André Luis Menezes; Silva, José Alexsandro da; Lira, Ana Amélia Moreira; Conceição, Tamara Matos Freire; Nunes, Rogéria de Souza; de Albuquerque Junior, Ricardo Luiz Cavalcanti; Sarmento, Victor Hugo Vitorino; Leal, Leila Bastos; de Santana, Davi Pereira

    2016-07-01

    This study proposed to investigate and to compare colloidal carrier systems containing Zidovudine (3'-azido-3'-deoxythymidine) (AZT) for transdermal administration and optimization of antiretroviral therapy. Microemulsion (ME) and lamellar phase (LP) liquid crystal were obtained and selected from pseudoternary diagrams previously developed. Small-angle X-ray scattering and rheology analysis confirmed the presence of typical ME and liquid crystalline structures with lamellar arrangement, respectively. Both colloidal carrier systems, ME, and LP remained stable, homogeneous, and isotropic after AZT addition. In vitro permeation study (using pig ear skin) showed that the amount of permeated drug was higher for ME compared to the control and LP, obtaining a permeation enhancing effect on the order of approximately 2-fold (p < 0.05). Microscopic examination after in vivo skin irritation studies using mice suggested few histological changes in the skin of animals treated with the ME compared to the control group (hydrogel). Thus, ME proved to be adequate and have promising effects, being able to promote the drug permeation without causing apparent skin irritation. On the order hand, LP functioned as a drug reservoir reducing AZT partitioning into the skin. PMID:27220471

  6. Facile dispersion and control of internal structure in lyotropic liquid crystalline particles by auxiliary solvent evaporation.

    Science.gov (United States)

    Martiel, Isabelle; Sagalowicz, Laurent; Handschin, Stephan; Mezzenga, Raffaele

    2014-12-01

    Submicron sized, structured lyotropic liquid crystalline (LLC) particles, so-called hexosomes and cubosomes, are generally obtained by high energy input dispersion methods, notably ultrasonication and high-pressure emulsification. We present a method to obtain dispersions of such LLC particles with a significantly reduced energy input, by evaporation of an auxiliary volatile solvent immiscible with water, e.g. cyclohexane or limonene. The inner structure of the particles can be precisely controlled by the addition of a nonvolatile oil, such as α-tocopherol or tetradecane consistently with bulk phase diagrams,. Two different lyotropic surfactants were employed, industrial grade monolinoleine (MLO) and soy bean phosphatidylcholine (PC). The lyotropic surfactant and oil phase modifier were first dissolved in the volatile solvent to give a liquid reverse micellar (L2) phase, which requires significantly less energy input to be dispersed in an aqueous solution of secondary emulsifier compared to the corresponding gel-like bulk mesophase. The auxiliary volatile solvent was then removed from the emulsion by evaporation at room temperature, yielding LLC particles of the desired inner structure, Pn3̅m, H2, or Fd3̅m. The obtained particles were characterized by small-angle X-ray scattering (SAXS), dynamic light scattering (DLS), and cryogenic transmission electron microscopy (cryo-TEM). Our method enables fine-tuning of the final particle size through the volatile-to-nonvolatile volume ratio and processing conditions. PMID:25384248

  7. Optical Input/Electrical Output Memory Elements based on a Liquid Crystalline Azobenzene Polymer.

    Science.gov (United States)

    Mosciatti, Thomas; Bonacchi, Sara; Gobbi, Marco; Ferlauto, Laura; Liscio, Fabiola; Giorgini, Loris; Orgiu, Emanuele; Samorì, Paolo

    2016-03-01

    Responsive polymer materials can change their properties when subjected to external stimuli. In this work, thin films of thermotropic poly(metha)acrylate/azobenzene polymers are explored as active layer in light-programmable, electrically readable memories. The memory effect is based on the reversible modifications of the film morphology induced by the photoisomerization of azobenzene mesogenic groups. When the film is in the liquid crystalline phase, the trans → cis isomerization induces a major surface reorganization on the mesoscopic scale that is characterized by a reduction in the effective thickness of the film. The film conductivity is measured in vertical two-terminal devices in which the polymer is sandwiched between a Au contact and a liquid compliant E-GaIn drop. We demonstrate that the trans → cis isomerization is accompanied by a reversible 100-fold change in the film conductance. In this way, the device can be set in a high- or low-resistance state by light irradiation at different wavelengths. This result paves the way toward the potential use of poly(metha)acrylate/azobenzene polymer films as active layer for optical input/electrical output memory elements. PMID:26890532

  8. PbTiO.sub.3./sub. nanoparticles embedded in a liquid crystalline elastomer matrix: structural and ordering properties

    Czech Academy of Sciences Publication Activity Database

    Domenici, V.; Zupančič, B.; Laguta, Valentyn; Belous, A. G.; Vyunov, O. I.; Remškar, M.; Zalar, B.

    2010-01-01

    Roč. 114, č. 24 (2010), s. 10782-10789. ISSN 1932-7447 Grant ostatní: EU EIF ELACEM(XE) 039643 Institutional research plan: CEZ:AV0Z10100521 Keywords : liquid crystalline elastomers * nanoparticles Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.520, year: 2010

  9. The effect of calcining temperature on the properties of 0-3 piezoelectric composites of PZT and a liquid crystalline thermosetting polymer

    NARCIS (Netherlands)

    Ende, D.A. van den; Groen, W.A.; Zwaag, S. van der

    2011-01-01

    We report on the optimisation of a recently developed high performance 0-3 piezoelectric composite comprising of the piezoelectric Lead Zirconate Titanate (PZT) powder and a liquid crystalline thermosetting matrix polymer (LCT). The matrix polymer is a liquid crystalline polymer comprising of an HBA

  10. Synthesis and characterization of liquid-crystalline supramolecular architecture by a combination of molecular recognition and polymerization reaction

    Science.gov (United States)

    Ahn, Cheol-Hee

    In nature, self-assembly with well defined shapes obtained from combinations of polymeric building blocks with complex architecture are abundant since they are responsible for the production of structural materials and for the generation of some of the most efficient mechanisms. One of the many roles liquid crystallinity plays in natural systems is in their self-assembly and organization. The assembly of these complex natural systems is largely under thermodynamic control which is manipulated by their liquid crystallinity. The goal of this thesis is to use Nature as a model for the development of new synthetic concepts and strategies in the field of polymer science. The two models selected are rod-like and icosahedral viruses. The strategy involved in this thesis requires the design of libraries of monodendritic building blocks with well defined flat tapered and conical shapes which self-assemble into cylindrical and respectively spherical shapes. By analogy with viruses these supermolecules will generated hexagonal columnar and spherical cubic thermotropic phases. These liquid crystalline phases allow the determination of their shape by X-ray diffraction and Scanning Force Microscopy. Libraries of flat tapered and conical monodendritic building blocks will be functionalized with polymerizable groups and polymerized to generate the first examples of polymers of cylindrical and spherical shapes with diameter and length, and diameter controlled at the nanoscale level. The organization of these dendritic monomers in a liquid crystalline assembly is also used to aggregate their polymerizable groups in a reactor of artificially enhanced concentration and restricted geometry during the polymerization process and therefore, generate a new approach to the control of polymerization. The resulting liquid crystallinity provides access to the thermodynamically controlled assembly and characterization of these newly developed polymers. With few exceptions, there is no precedent

  11. Lyotropic Mesomorphisms of a Lamellar Liquid Crystalline Phase in Non-hydrous Condition: A Phospholipid Hydrated by Different Polar Solvents

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dong Kyu [Korea Kolmar Corporation, Yongi (Korea, Republic of); Jeong, Kwan Young [Chung-buk University, Cheongju (Korea, Republic of)

    2010-05-15

    The lyotropic mesomorphism of lamellar liquid crystalline phase was examined by observing the swelling behavior of Distearoylphosphatidylcholine(DSPC) in glycerin and panthenol without water. The lyotropic mesomorphism was examined by using DSC, XRDs and Cryo-SEM. Increase of two polar solvents under non-hydrous condition showed distinctive differences in the lyotropic mesomorphism from forming different anisotropic structures with DSPC. Glycerin did not affect to the crystalline region of lamellar phase, whereas typical swelling mesomorphism was shown in the noncrystalline region. In contrast, panthenol showed some effect on the crystalline region, but common swelling mesomorphism was found in the non-crystalline region. In this case, the isopropyl and propyl groups in panthenol were the main factor to affect to the lipophilic domain in the crystalline region of lamellar phase. Also, it was found that the formation of well-arranged lamellar structure only by introducing glycerin and panthenol as a solvent without water, was possible. These results were confirmed by examination of the swelling mesomorphism of liquid crystal membrane triggered by introducing the two polar solvents.

  12. Self-assembled multicompartment liquid crystalline lipid carriers for protein, peptide, and nucleic acid drug delivery.

    Science.gov (United States)

    Angelova, Angelina; Angelov, Borislav; Mutafchieva, Rada; Lesieur, Sylviane; Couvreur, Patrick

    2011-02-15

    Lipids and lipopolymers self-assembled into biocompatible nano- and mesostructured functional materials offer many potential applications in medicine and diagnostics. In this Account, we demonstrate how high-resolution structural investigations of bicontinuous cubic templates made from lyotropic thermosensitive liquid-crystalline (LC) materials have initiated the development of innovative lipidopolymeric self-assembled nanocarriers. Such structures have tunable nanochannel sizes, morphologies, and hierarchical inner organizations and provide potential vehicles for the predictable loading and release of therapeutic proteins, peptides, or nucleic acids. This Account shows that structural studies of swelling of bicontinuous cubic lipid/water phases are essential for overcoming the nanoscale constraints for encapsulation of large therapeutic molecules in multicompartment lipid carriers. For the systems described here, we have employed time-resolved small-angle X-ray scattering (SAXS) and high-resolution freeze-fracture electronic microscopy (FF-EM) to study the morphology and the dynamic topological transitions of these nanostructured multicomponent amphiphilic assemblies. Quasi-elastic light scattering and circular dichroism spectroscopy can provide additional information at the nanoscale about the behavior of lipid/protein self-assemblies under conditions that approximate physiological hydration. We wanted to generalize these findings to control the stability and the hydration of the water nanochannels in liquid-crystalline lipid nanovehicles and confine therapeutic biomolecules within these structures. Therefore we analyzed the influence of amphiphilic and soluble additives (e.g. poly(ethylene glycol)monooleate (MO-PEG), octyl glucoside (OG), proteins) on the nanochannels' size in a diamond (D)-type bicontinuous cubic phase of the lipid glycerol monooleate (MO). At body temperature, we can stabilize long-living swollen states, corresponding to a diamond cubic phase

  13. Organic solar cells based on liquid crystalline and polycrystalline thin films

    Science.gov (United States)

    Yoo, Seunghyup

    This dissertation describes the study of organic thin-film solar cells in pursuit of affordable, renewable, and environmentally-friendly energy sources. Particular emphasis is given to the molecular ordering found in liquid crystalline or polycrystalline films as a way to leverage the efficiencies of these types of cells. Maximum efficiencies estimated based on excitonic character of organic solar cells show power conversion efficiencies larger than 10% are possible in principle. However, their performance is often limited due to small exciton diffusion lengths and poor transport properties which may be attributed to the amorphous nature of most organic semiconductors. Discotic liquid crystal (DLC) copper phthalocyanine was investigated as an easily processible building block for solar cells in which ordered molecular arrangements are enabled by a self-organization in its mesophases. An increase in photocurrent and a reduction in series resistance have been observed in a cell which underwent an annealing process. X-ray diffraction (XRD) and atomic force microscopy (AFM) measurements suggest that structural and morphological changes induced after the annealing process are related to these improvements. In an alternative approach, p-type pentacene thin films prepared by physical vapor deposition were incorporated into heterojunction solar cells with C60 as n-type layers. Power conversion efficiencies of 2.7% under broadband illumination (350--900 nm) with a peak external quantum efficiency of 58% have been achieved with the broad spectral coverage across the visible spectrum. Analysis using an exciton diffusion model shows this efficient carrier generation is mainly due to the large exciton diffusion length of pentacene films. Joint XRD and AFM studies reveal that the highly crystalline nature of pentacene films can account for the observed large exciton diffusion length. In addition, the electrical characteristics are studied as a function of light intensity using

  14. Local order and orientational correlations in liquid and crystalline phases of carbon tetrabromide from neutron powder diffraction measurements

    Science.gov (United States)

    Temleitner, L.; Pusztai, L.

    2010-04-01

    The liquid, plastic crystalline and ordered crystalline phases of CBr4 were studied using neutron-powder diffraction. The measured total scattering differential cross sections were modeled by reverse Monte Carlo simulation techniques ( RMC++ and RMCPOW). Following successful simulations, the single-crystal-diffraction pattern of the plastic phase as well as partial radial distribution functions and orientational correlations for all the three phases have been calculated from the atomic coordinates (particle configurations). The single-crystal pattern, calculated from a configuration that had been obtained from modeling the powder pattern, shows identical behavior to the recent single-crystal data of Folmer [Phys. Rev. B 77, 144205 (2008)]. The BrBr partial radial-distribution functions of the liquid and plastic crystalline phases are almost the same while CC correlations clearly display long-range ordering in the latter phase. Orientational correlations also suggest strong similarities between liquid and plastic crystalline phases whereas the monoclinic phase behaves very differently. Orientations of the molecules are distinct in the ordered phase whereas in the plastic crystal their distribution seems to be isotropic.

  15. Examining the gastrointestinal transit of lipid-based liquid crystalline systems using whole-animal imaging.

    Science.gov (United States)

    Pham, Anna C; Nguyen, Tri-Hung; Nowell, Cameron J; Graham, Bim; Boyd, Ben J

    2015-12-01

    Lipid-based liquid crystalline (LC) systems have the potential to sustain the oral absorption of poorly water-soluble drugs in vivo, facilitating slow drug release from their complex internal structure. To further evaluate the dynamic relationship between gastric retention and sustained drug absorption for these systems, this study aimed to explore non-invasive X-ray micro-CT imaging as an approach to assess gastric retention. Pharmacokinetic studies were also conducted with cinnarizine-loaded LC formulations to correlate gastric retention of the formulation to drug absorption. The in vivo studies demonstrated the interplay between gastric retention and drug absorption based on the digestibility of the LC structures. An increase in non-digestible phytantriol (PHY) composition in the formulation relative to digestible glyceryl monooleate (GMO) increased the gastric retention, with 68 ± 4 % of formulation intensity remaining at 8 h for 85 % w/w PHY, and 26 ± 9 % for 60 % w/w PHY. Interestingly, it was found that PHY 30 % w/w in GMO provided the highest bioavailability for cinnarizine (CZ) amongst the other combinations, including GMO alone. The studies demonstrated that combining digestible and non-digestible lipids into LC systems allowed for an optimal balance between sustaining drug absorption whilst increasing plasma concentration (C max) over time, leading to enhanced oral bioavailability. The results demonstrate the potential for utilising non-invasive X-ray micro-CT imaging to dynamically assess the GI transit of orally administered liquid crystal-forming formulations. PMID:26328930

  16. Magneto-responsive liquid crystalline elastomer nanocomposites as potential candidates for dynamic cell culture substrates.

    Science.gov (United States)

    Herrera-Posada, Stephany; Mora-Navarro, Camilo; Ortiz-Bermudez, Patricia; Torres-Lugo, Madeline; McElhinny, Kyle M; Evans, Paul G; Calcagno, Barbara O; Acevedo, Aldo

    2016-08-01

    Recently, liquid crystalline elastomers (LCEs) have been proposed as active substrates for cell culture due to their potential to attach and orient cells, and impose dynamic mechanical signals through the application of external stimuli. In this report, the preparation of anisotropic and oriented nematic magnetic-sensitized LCEs with iron oxide nanoparticles, and the evaluation of the effect of particle addition at low concentrations on the resultant structural, thermal, thermo-mechanical, and mechanical properties is presented. Phase transformations produced by heating in alternating magnetic fields were investigated in LCEs in contact with air, water, and a common liquid cell culture medium was also evaluated. The inclusion of nanoparticles into the elastomers displaced the nematic-to-isotropic phase transition, without affecting the nematic structure as evidenced by similar values of the order parameter, while reducing the maximum thermomechanical deformations. Remote and reversible deformations of the magnetic LCEs were achieved through the application of alternating magnetic fields, which induces the nematic-isotropic phase transition through nanoparticle heat generation. Formulation parameters can be modified to allow for remote actuation at values closer to the human physiological temperature range and within the range of deformations that can affect the cellular behavior of fibroblasts. Finally, a collagen surface treatment was performed to improve compatibility with NIH-3T3 fibroblast cultures, which enabled the attachment and proliferation of fibroblasts on substrates with and without magnetic particles under quiescent conditions. The LCEs developed in this work, which are able to deform and experience stress changes by remote contact-less magnetic stimulation, may allow for further studies on the effect of substrate morphology changes and dynamic mechanical properties during in vitro cell culture. PMID:27157764

  17. Non-covalent modification of reduced graphene oxide by a chiral liquid crystalline surfactant.

    Science.gov (United States)

    Lin, Pengcheng; Cong, Yuehua; Sun, Cong; Zhang, Baoyan

    2016-01-28

    In order to effectively disperse reduced graphene oxide (RGO) in functional materials and take full advantage of its exceptional physical and chemical properties, a novel and effective approach for non-covalent modification of RGO by a chiral liquid crystalline surfactant (CLCS) consisting of chiral mesogenic units, nematic mesogenic units with carboxyl groups and non-mesogenic units with a polycyclic conjugated structure is firstly established. The polycyclic conjugated structure can anchor onto the RGO surface via π-π interactions, the chiral mesogenic units possess affinity for chiral materials by joining the helical matrix of chiral material and the carboxyl groups in nematic mesogenic units are supposed to form coordination bonds with nano zinc oxide (ZnO) to fabricate functional nano hybrids. The transmittances of CLCS-RGO hybrids exhibit S-shaped nonlinear increase with the increase of wavelength, but the total transmittances from 220 nm to 800 nm show a linear decreasing trend with the increase of RGO content in the CLCS-RGO hybrid. Due to the superior thermal properties of RGO and the interactions between RGO and CLCS, the dispersed RGO can improve the glass transition and increase the thermal stability and decomposition activation energy of CLCS. The intercalation of RGO can decrease the thermochromism temperature and improve the pitch uniformity of CLCS. Furthermore, CLCS can promote the dispersion of RGO in chiral nematic liquid crystals (CNLCs), and the CNLC-RGO-CLCS hybrids present decreased driving voltage and accelerated electro-optical response. The CLCS non-covalently modified RGO can strengthen the photocatalytic degradation of ZnO by suppressing the aggregation of ZnO and RGO. PMID:26754831

  18. Thermal diffusivity of hexagonal boron nitride composites based on cross-linked liquid crystalline polyimides.

    Science.gov (United States)

    Shoji, Yu; Higashihara, Tomoya; Tokita, Masatoshi; Morikawa, Junko; Watanabe, Junji; Ueda, Mitsuru

    2013-04-24

    Hexagonal boron nitride (h-BN) composites with the oriented cross-linked liquid crystalline (LC) polyimide have been developed as high thermally conductive materials. Well-dispersed h-BN composite films were obtained, as observed by scanning electron microscopy. The morphology of the composite films was further investigated in detail by the wide-angle X-ray diffraction. The obtained composite films based on the cross-linked LC polyimide showed that the polymer chains vertically aligned in the direction parallel to the films, while those based on the amorphous polyimide showed an isotropic nature. Moreover, the alignment of the cross-linked LC polyimides was maintained, even after increasing the volume fraction of h-BN. This alignment plays an important role in the effective phonon conduction between h-BN and the matrices. Indeed, the thermal diffusivity in the thickness direction of the composite films based on the LC polyimide measured by a temperature wave analysis method was increased to 0.679 mm(2) s(-1) at a 30 vol % h-BN loading, which was higher than that based on the amorphous polyimide. PMID:23506319

  19. Unique effect of an electric field on a new liquid crystalline lactic acid derivative.

    Science.gov (United States)

    Novotná, Vladimíra; Glogarová, Milada; Kašpar, Miroslav; Hamplová, Věra; Lejček, Lubor; Pociecha, Damian

    2015-06-21

    A new chiral lactic acid derivative is presented, exhibiting a frustrated liquid crystalline phase, namely the orthogonal twist grain boundary TGBA phase in a broad temperature interval. A unique effect is observed that the applied electric field reversibly transforms the planar TGBA texture to the homeotropic one, homogeneously dark in crossed polarizers. The transformation is analogous to the Frederiks transition known in nematics, in which switching under electric field is driven by the positive dielectric anisotropy. A similar effect is established also in the SmA phase of the racemic mixture, where the field induced transformation is irreversible. A positive dielectric anisotropy in both the chiral compound and the racemic mixture is detected up to the frequency of about 10 kHz, above this frequency the anisotropy is negative. The unusual behavior of the TGBA phase under the electric field can be explained by the specific packing of molecules within the smectic layers, resulting in a relatively high layer compressibility which lowers the energy of the structural defects and thus facilitates the structure transformation. The perfectly dark state of the studied compounds, induced by the electric field, either stable or reversible, is appealing for specific applications. The change of the sign of the dielectric anisotropy, known in nematics as the dual frequency effect, might be important for photonics such as adaptive or diffractive optics. PMID:25968628

  20. Homogeneous alignment of liquid crystalline dendrimers confined in a slit-pore. A simulation study

    International Nuclear Information System (INIS)

    In this work we present results from isobaric-isothermal (NPT) Monte Carlo simulation studies of model liquid crystalline dendrimer (LCDr) systems confined in a slit-pore made of two parallel flat walls. The dendrimers are modelled as a collection of spherical and ellipsoidal particles corresponding to the junction points of the dendritic core and to the mesogenic units respectively. Assuming planar uniform (unidirectional) soft anchoring of the mesogenic units on the substrates we investigate the conformational and alignment properties of the LCDr system at different thermodynamic state points. Tractable coarse grained force fields have been used from our previous work. At low pressures the interior of the pore is almost empty, since almost all LCDrs are anchored to the substrates forming two-dimensional smectic-like structures with the mesogens aligned along the aligning direction of the substrates. As the pressure grows the LCDrs occupy the whole pore. However, even at low temperatures, the smectic organization does not transmit in the interior of the pore and is preserved for distances of 2–3 mesogenic diameters from the walls. For this reason, the global orientational order decreases with increasing pressure (density). In the vicinity (2–3 mesogenic diameters) of the pore walls, mesogenic units preserve the smectic structure whose layers are separated by layers of spherical beads. In this region individual LCDrs possess a rod like shape. (paper)

  1. From soft to hard rod behavior in liquid crystalline suspensions of sterically stabilized colloidal filamentous particles.

    Science.gov (United States)

    Grelet, Eric; Rana, Richa

    2016-05-18

    The liquid crystalline phase behavior of a colloidal system of sterically stabilized rods is reported. Our colloidal suspensions consist of highly monodisperse, semi-flexible filamentous viruses which have been coated with neutral hydrophilic polymers by irreversibly binding poly(ethylene glycol) (PEG) to the surface of the virus particles. Depending on the size of the grafted polymer, up to three different phase transitions are observed (isotropic-to-chiral nematic, chiral nematic-to-smectic, and smectic-to-columnar). Each phase transition is shown to be independent of ionic strength, confirming the steric stabilization of the viral colloids. A direct, i.e. without any free parameters, comparison with theory and computer simulations of the volume fraction associated with the phase transition can be performed, showing a quantitative agreement with hard rod behavior at a low polymer chain size, and some deviation stemming from soft repulsion by increasing the polymer thickness coating of the rod. Specifically, we demonstrate that the columnar mesophase is not stabilized by electrostatic repulsion, and we discuss the conditions of its existence. PMID:27108523

  2. Homogeneous alignment of liquid crystalline dendrimers confined in a slit-pore. A simulation study

    Science.gov (United States)

    Workineh, Zerihun G.; Vanakaras, Alexandros G.

    2016-03-01

    In this work we present results from isobaric-isothermal (NPT) Monte Carlo simulation studies of model liquid crystalline dendrimer (LCDr) systems confined in a slit-pore made of two parallel flat walls. The dendrimers are modelled as a collection of spherical and ellipsoidal particles corresponding to the junction points of the dendritic core and to the mesogenic units respectively. Assuming planar uniform (unidirectional) soft anchoring of the mesogenic units on the substrates we investigate the conformational and alignment properties of the LCDr system at different thermodynamic state points. Tractable coarse grained force fields have been used from our previous work. At low pressures the interior of the pore is almost empty, since almost all LCDrs are anchored to the substrates forming two-dimensional smectic-like structures with the mesogens aligned along the aligning direction of the substrates. As the pressure grows the LCDrs occupy the whole pore. However, even at low temperatures, the smectic organization does not transmit in the interior of the pore and is preserved for distances of 2-3 mesogenic diameters from the walls. For this reason, the global orientational order decreases with increasing pressure (density). In the vicinity (2-3 mesogenic diameters) of the pore walls, mesogenic units preserve the smectic structure whose layers are separated by layers of spherical beads. In this region individual LCDrs possess a rod like shape.

  3. Electrically Conductive Compounds of Polycarbonate, Liquid Crystalline Polymer, and Multiwalled Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Penwisa Pisitsak

    2012-01-01

    Full Text Available A thermotropic liquid crystalline polymer (LCP was blended with polycarbonate (PC and multiwalled carbon nanotube (CNT with the goal of improving electrical conductivity and mechanical properties over PC. The LCP was anticipated to produce fibrillar domains in PC and help improve the mechanical properties. The study was carried out using two grades of LCP—Vectra A950 (VA950 and Vectra V400P (V400P. The compounds contained 20 wt% LCP and 0.5 to 15 wt% CNT. The compounds were prepared by melt-blending in a twin-screw minicompounder and then injection molded using a mini-injection molder. The fibrillar domains of LCP were found only in the case of PC/VA950 blend. However, these fibrils turned into droplets in the presence of CNT. It was found that CNT preferentially remained inside the LCP domains as predicted from the value of spreading coefficient. The electrical conductivity showed the following order with the numbers in parenthesis representing the electrical percolation threshold of the compounds: PC/CNT (1% > PC/VA950P/CNT (1% > PC/V400P/CNT (3%. The storage modulus showed improvements with the addition of CNT and VA950.

  4. STUDY ON INTERMITTENT SHEAR FLOW AND RELAXATION BEHAVIOR OF THERMOTROPIC LIQUID CRYSTALLINE POLYMER

    Institute of Scientific and Technical Information of China (English)

    Ruo-Bing Yu; Chi-Xing Zhou; Wei Yu

    2005-01-01

    Intermittent shear flow including start-up flow and small oscillatory amplitude time sweep or stress relaxation after cessation of shear flow was used to study the rheological behavior and internal structure of thermotropic liquid crystalline polymer (TLCP). There are two kinds of intermittent shear flow: all start-up flows are in the same direction (intermittent flow forward: IFF) and start-up flows change their directions alternately (intermittent flow reversal: IFR). The results show that the stress of start-up flow of IFF and IFR in the test process is not superposed, indicating different changes of internal structure of thermotropic LCP (TLCP). Two main factors affect structure changes in the experimental time scale. One relates to long-term texture relaxation process, the other is an interchain reaction that becomes important after 30 min. The two factors raise the stress of IFF, but express complex effects for the stress of IFR. The latter factor becomes very important at long time annealing process. The relaxation behavior was also studied by the application of wide range relaxation spectrum calculated from the combined dynamic modulus, which gave three characteristic relaxation times (0.3, 10 and 600 s)ascribable to the relaxations of less-phase orientation, domain orientation, and domain deformation, respectively. The result also shows that the domain coalescence (texture relaxation), a long relaxation time, is a much slow process and lasts beyond 2400 s of the test time.

  5. Effects of Flexibility on Liquid Crystalline Polymer Behavior: The Nematic Broken Road

    Science.gov (United States)

    Leal, L. Gary; Charuv, Chaubal

    1998-03-01

    A new theory for Liquid Crystalline Polymers is developed and its behavior in simple shear flow is analyzed. The theory accounts for molecular flexibility by employing a microstructure consisting of two rigid rods linked by a joint with a tunable stiffness. The probability distribution function equation for the orientation of the arms of the broken rod is derived. The adaptation of the Smoothed Particle Hydrodynamics (SPH) technique for obtaining numerical solutions to this theory is detailed. The behavior of the theory at equilibrium is derived analytically and compared with numerical results; the SPH technique is then used to obtain results in flow. It is found that in the limit of a nearly stiff joint, the model gives behavior that is very similar to that of rigid rod polymers, the only difference being a lesser tendency to tumble due to greater variation in the order parameter. For nearly free joints, the shear flow induces interesting dynamics for the transition between states with the arms outstretched and those where they are folded up (so-called ''hairpins'' of main-chain LCPs).

  6. Effect of Phase Transition on the Rheology of Model Thermotropic Liquid Crystalline Polymers

    Science.gov (United States)

    Zhou, Weijun; Kornfield, Julie A.

    1998-03-01

    Despite their important material properties, rheological studies of thermotropic liquid crystalline polymers (TLCPs) have not received much attention due to experimental difficulties. In this report, we describe the rheology of a model TLCP, which has good thermal stability and low isotropization temperature (DHMS-7,9, T_m=90^circC, T_xn=120^circC, T_ni=197^circC, where T_xn is the transition temperature between an unidentified mesophase to nematic phase). Systematic studies were carried out on DHMS-7,9 as a function of temperature and Mw (M_w=11K to 65K). Oscillatory dynamic moduli (G^') showed a plateau at an intermediate frequency at temperature below 120^circC , but no plateau for G^' was observed over the whole frequency range studied above 120^circC. We also studied the corresponding textural behavior by rheological-microscopy at different temperature with a home-made flow cell attached to a polarized light microscopy. It was recently reported that this TLCP exhibits different flow-aligning behavior in the mesophase by X-ray diffraction (Log-rolling alignment below 120^circC and typical flow alignment above 120^circC). Currently, we are investigating the origin of this flow behavior.

  7. Three-dimensional flow of liquid crystalline polymers through rectangular channels with abrupt change in geometry

    Science.gov (United States)

    Yamamoto, Takehiro; Yamasaki, Yasuo; Tanaka, Yusuke; Mori, Noriyasu

    2006-07-01

    Three-dimensional flows of liquid crystalline polymers (LCPs) in a rectangular 3 to 1 abrupt contraction channel and a rectangular 1 to 3 abrupt expansion channel are numerically analyzed to investigate the molecular orientation behavior of LCPs in complex flows. A modified Doi model is used as a constitutive equation and MAC (marker and cell)-based finite difference method is employed for the numerical technique for solving the basic equations. In the contraction flow, most molecules are aligned in the flow direction near the contraction owing to elongational flow except for a vortex region. Just downstream of the contraction, the velocity overshoot occurs owing to the molecular orientation near the contraction. In the expansion flow, on the other hand, molecules near the mid-plane are aligned perpendicular to the flow direction just downstream of the expansion. This alignment is related to a concave velocity profile appeared in this region. Moreover, the decelerating flow downstream of the expansion causes a three-dimensional structure of directors called a twist structure.

  8. A molecular nematic liquid crystalline material for high-performance organic photovoltaics

    Science.gov (United States)

    Sun, Kuan; Xiao, Zeyun; Lu, Shirong; Zajaczkowski, Wojciech; Pisula, Wojciech; Hanssen, Eric; White, Jonathan M.; Williamson, Rachel M.; Subbiah, Jegadesan; Ouyang, Jianyong; Holmes, Andrew B.; Wong, Wallace W. H.; Jones, David J.

    2015-01-01

    Solution-processed organic photovoltaic cells (OPVs) hold great promise to enable roll-to-roll printing of environmentally friendly, mechanically flexible and cost-effective photovoltaic devices. Nevertheless, many high-performing systems show best power conversion efficiencies (PCEs) with a thin active layer (thickness is ~100 nm) that is difficult to translate to roll-to-roll processing with high reproducibility. Here we report a new molecular donor, benzodithiophene terthiophene rhodanine (BTR), which exhibits good processability, nematic liquid crystalline behaviour and excellent optoelectronic properties. A maximum PCE of 9.3% is achieved under AM 1.5G solar irradiation, with fill factor reaching 77%, rarely achieved in solution-processed OPVs. Particularly promising is the fact that BTR-based devices with active layer thicknesses up to 400 nm can still afford high fill factor of ~70% and high PCE of ~8%. Together, the results suggest, with better device architectures for longer device lifetime, BTR is an ideal candidate for mass production of OPVs.

  9. Ophthalmic delivery of brinzolamide by liquid crystalline nanoparticles: in vitro and in vivo evaluation.

    Science.gov (United States)

    Wu, Weijun; Li, Jing; Wu, Lin; Wang, Baoyan; Wang, Zhongyuan; Xu, Qunwei; Xin, Hongliang

    2013-09-01

    Brinzolamide (BLZ) is a drug used to treat glaucoma; however, its use is restricted due to some unwanted adverse events. The goal of this study was to develop BLZ-loaded liquid crystalline nanoparticles (BLZ LCNPs) and to figure out the possibility of LCNPs as a new therapeutic system for glaucoma. BLZ LCNPs were produced by a modified emulsification method and their physicochemical aspects were estimated. In vitro release study revealed BLZ LCNPs displayed to some extent prolonged drug release behavior in contrast to that of BLZ commercial product (Azopt®). The ex vivo apparent permeability coefficient of BLZ LCNP systems demonstrated a 3.47-fold increase compared with that of Azopt®. The pharmacodynamics was checked over by calculating the percentage fall in intraocular pressure and the pharmacodynamic test showed that BLZ LCNPs had better therapeutic potential than Azopt®. Furthermore, the in vivo ophthalmic irritation was evaluated by Draize test. In conclusion, BLZ LCNPs would be a promising delivery system used for the treatment of glaucoma, with advantages such as lower doses but maintaining the effectiveness, better ocular bioavailability, and patient compliance compared with Azopt®. PMID:23813437

  10. Topological defects in liquid crystalline matter: Strain transitions, simulations, and visualization of core structure and fluctuations

    Science.gov (United States)

    Callan-Jones, Andrew

    Topological defects play several roles in the physics of liquid crystalline matter. Their presence is felt over many length scales, necessitating modeling strategies ranging from continuum level finite element analysis of cholesteric elastomers to molecular dynamics simulation of liquid nematics. We have first studied the effect of a strain applied to a cholesteric elastomer, focusing on the transition from the twisted phase to the nematic phase, and extended work by others by including the Frank penalty for director distortions. This leads to metastability of the twisted state above the transition, prompting us to consider nucleation of topological defects as way to remove the twist walls. We explored the consequences of this idea and obtained analytical and numerical agreement, concluding that inhomogeneities in the strain field due to the coexisting phases are small, making the nucleation problem very similar to earlier studies on cholesteric liquids unwound by a magnetic field. Molecular dynamics simulations of a temperature quench of a fluid of rod-like molecules based on the Gay-Berne potential provide a way to study multiscale phenomena associated with defects, such as the structure of the core and the interaction between defect motion and the underlying orientational degrees of freedom. Locating and then studying defects in a fluid, as opposed to in a lattice simulation, however, are inherently challenging problems because of the mobility of the molecules. We have collaborated with researchers in scientific visualization to develop methods that overcome limitations of an earlier discrete finding method. In particular, new measures for describing nematic ordering are introduced, making observation of features such as the defect type and the nature of the core readily done. The dramatic improvement in spatial and temporal resolution of defect behavior afforded by the visualization opens up a number of possible routes to follow in studying static and dynamic

  11. Processing, structure and property relationships in commercial thermotropic liquid crystalline polymers

    Science.gov (United States)

    Rendon, Stanley

    Thermotropic liquid crystalline polymers (TLCPs) offer considerable promise as high strength/lightweight engineering materials. Their excellent mechanical properties are derived from the spontaneous ordering of stiff polymer molecules in the melt state, which is ultimately translated into high molecular orientation in finished products. Understanding the effect of processing on molecular orientation, and specifically the role and mechanisms by which flow fields impact molecular orientation, is thus a prerequisite to rational design of processes that exploit and enhance the characteristics of TLCPs. The lack of fundamental knowledge to rationally anticipate structure development during processing of commercial main-chain TLCPs however, has significantly hindered the wide spread applicability of these materials. In light of the need for improved understanding of flow-orientation relationships in TLCPs, this thesis presents the first coordinated attempt to combine fundamental studies of orientation development in well-defined simple flows (simple shear) and complex processing flows (extrusion and injection molding) using in situ x-ray scattering methods, with structure and property investigations of injection molded plaques made from commercial TLCPs. The work described here addresses fundamental questions related to the shear-alignment behavior of several commercial (Vectra A950RTM, Vectra B950RTM) and pre-commercial (DHalphaMS) thermotropes. The use of well-established in situ x-ray scattering methods previously developed in the Burghardt group, has enabled us to probe the evolution of molecular orientation under the influence of various transient shear flow protocols some of which provide strong, indirect evidence of flow-tumbling behavior in Vectra copolyesters. In situ orientation studies in steady isothermal complex channel flows reveal that superposition of extensional gradients on the inhomogeneous shear of pressure-driven slit flows dramatically influences

  12. Chronic intermittent hypoxia creates the perfect storm with calamitous consequences for respiratory control.

    Science.gov (United States)

    O'Halloran, Ken D

    2016-06-01

    Obstructive sleep apnoea syndrome (OSAS) is a common respiratory disorder with devastating consequences for integrative body systems. A picture is emerging to illustrate wide-ranging deleterious consequences of disordered breathing during sleep for major homeostatic control systems, with considerable interest in cardiorespiratory and autonomic morbidity underpinning the development of hypertension. The vista is bleak when one also considers the link between OSAS and a host of other maladies. Exposure to chronic intermittent hypoxia (CIH), resulting from repeated obstructions of the pharyngeal airway, is a hallmark feature of OSAS that appears, in animal models, to drive the development and maintenance of several key morbidities. A growing body of evidence now points to aberrant respiratory plasticity at multiple levels following exposure to CIH. Herein, we review the experimental data revealing that CIH causes: respiratory muscle weakness and fatigue; impaired motor control of the upper airway; and, discordant respiratory rhythm and pattern generation. This multifaceted conspiracy creates the perfect storm with the potential to exacerbate OSAS-serving to establish an inescapable cycle of respiratory morbidity. Several pharmacological interventions in animal models appear wholly effective in preventing the calamitous consequences of CIH and may have application as adjunctive therapies in the treatment of OSAS. PMID:26528897

  13. Liquid Crystalline Nanoparticles as an Ophthalmic Delivery System for Tetrandrine: Development, Characterization, and In Vitro and In Vivo Evaluation

    OpenAIRE

    Liu, Rui; Wang, Shuangshuang; Fang, Shiming; Wang, Jialu; Chen, Jingjing; Huang, Xingguo; He, Xin; Liu, Changxiao

    2016-01-01

    The purpose of this study was to develop novel liquid crystalline nanoparticles (LCNPs) that display improved pre-ocular residence time and ocular bioavailability and that can be used as an ophthalmic delivery system for tetrandrine (TET). The delivery system consisted of three primary components, including glyceryl monoolein, poloxamer 407, and water, and two secondary components, including Gelucire 44/14 and amphipathic octadecyl-quaternized carboxymethyl chitosan. The amount of TET, the am...

  14. Relaxation dynamics of the gel to liquid-crystalline transition of phosphatidylcholine bilayers. Effects of chainlength and vesicle size.

    OpenAIRE

    van Osdol, W W; Johnson, M.L.; Ye, Q.; Biltonen, R L

    1991-01-01

    The relaxation kinetics of the gel to liquid-crystalline transition of five phosphatidylcholine (DC14PC to DC18PC) bilayer dispersions have been investigated using volume perturbation calorimetry, a steady-state technique which subjects a sample to sinusoidal changes in volume. Temperature and pressure responses to the volume perturbation are measured to monitor the relaxation to a new equilibrium position. The amplitude demodulation and phase shift of these observables are analyzed with resp...

  15. The structure and phase transitions in polymer blends, diblock copolymers and liquid crystalline polymers: the Landau-Ginzburg approach

    OpenAIRE

    Holyst, Robert; Vilgis, T. A.

    1996-01-01

    The polymer systems are discussed in the framework of the Landau-Ginzburg model. The model is derived from the mesoscopic Edwards hamiltonian via the conditional partition function. We discuss flexible, semiflexible and rigid polymers. The following systems are studied: polymer blends, flexible diblock and multi-block copolymer melts, random copolymer melts, ring polymers, rigid-flexible diblock copolymer melts, mixtures of copolymers and homopolymers and mixtures of liquid crystalline polyme...

  16. Cholesteric liquid crystalline phases given by three helical biological polymers : DNA, PBLG and xanthan. A comparative analysis of their textures

    OpenAIRE

    Livolant, F.

    1986-01-01

    The cholesteric liquid crystalline phases of three polymers of biological interest have been investigated: PBLG (a polypeptide), DNA (a polynucleotide) and xanthan (a polysaccharide). The textures (and the defects which they contain) of these three mesophases are analysed and compared The main difference concerns focal lines which apparently do not occur in PBLG, are rare in DNA but occur frequently in xanthan. The frequency of occurrence of the different types of rotation and translation dis...

  17. Investigation of flow and microstructure in rheometric and processing flow conditions for liquid crystalline pitch

    Science.gov (United States)

    Kundu, Santanu

    The microstructure development within mesophase pitch-based carbon materials depends on the flow history that the pitch is subjected to. Therefore, a fundamental understanding of flow and its influence on the microstructure is required to obtain carbon materials with desired properties. The objective of this research was to investigate the flow and microstructural behavior of a synthetic mesophase pitch (AR-HP) in rheometric and processing flow conditions. In addition, simulation studies were performed to establish a frame work for modeling the flow behavior of this complex material in different flow situations. The steady-shear viscosities obtained from a cone-plate rheometer during increasing rate-sweep experiments exhibited shear-thinning (Region I) and plateau (Region II) responses. However, the slope of the shear-thinning region was only about -0.2, much lower than -0.5 observed in some pitches and liquid-crystalline polymers. This difference could arise from the different molecular constituents of pitches. At higher shear rates, as measured from capillary rheometers, the viscosity values remained almost constant. The transient shear stress responses, as measured from cone-plate rheometer, exhibited nonmonotonic behavior as a function of applied strain at all shear rates and temperatures tested. After rheological experiments, the samples were collected by developing a new experimental protocol for preservation of the sample for microstructural analysis. Microstructural observations obtained from three orthogonal sections, reported for the first time in the literature, indicate that the local maximum in shear stress was due to yielding of initial microstructure. The microstructure became flow oriented with further shearing, and the structure size decreased with increasing shear rates. In addition to high-strain experiments, dynamic experiments were also performed in the linear viscoelastic region where no significant deformation of fluid takes place. The

  18. Solvation Dynamics in Different Phases of the Lyotropic Liquid Crystalline System.

    Science.gov (United States)

    Roy, Bibhisan; Satpathi, Sagar; Gavvala, Krishna; Koninti, Raj Kumar; Hazra, Partha

    2015-09-01

    Reverse hexagonal (HII) liquid crystalline material based on glycerol monooleate (GMO) is considered as a potential carrier for drugs and other important biomolecules due to its thermotropic phase change and excellent morphology. In this work, the dynamics of encapsulated water, which plays important role in stabilization and formation of reverse hexagonal mesophase, has been investigated by time dependent Stokes shift method using Coumarin-343 as a solvation probe. The formation of the reverse hexagonal mesophase (HII) and transformation to the L2 phase have been monitored using small-angle X-ray scattering and polarized light microscopy experiments. REES studies suggest the existence of different polar regions in both HII and L2 systems. The solvation dynamics study inside the reverse hexagonal (HII) phase reveals the existence of two different types of water molecules exhibiting dynamics on a 120-900 ps time scale. The estimated diffusion coefficients of both types of water molecules obtained from the observed dynamics are in good agreement with the measured diffusion coefficient collected from the NMR study. The calculated activation energy is found to be 2.05 kcal/mol, which is associated with coupled rotational-translational water relaxation dynamics upon the transition from "bound" to "quasi-free" state. The observed ∼2 ns faster dynamics of the L2 phase compared to the HII phase may be associated with both the phase transformation as well as thermotropic effect on the relaxation process. Microviscosities calculated from time-resolved anisotropy studies infer that the interface is almost ∼22 times higher viscous than the central part of the cylinder. Overall, our results reveal the unique dynamical features of water inside the cylinder of reverse hexagonal and inverse micellar phases. PMID:26258397

  19. Transient molecular orientation and rheology in flow aligning thermotropic liquid crystalline polymers

    International Nuclear Information System (INIS)

    Quantitative measurements of molecular orientation and rheology are reported for various transient shear flows of a nematic semiflexible copolyether. Unlike the case of lyotropic liquid crystalline polymers (LCPs), whose structure and rheology in shear are dominated by director tumbling, this material exhibits flow aligning behavior. The observed behavior is quite similar to that seen in a copolyester that we have recently studied [Ugaz and Burghardt (1998)], suggesting that flow aligning dynamics may predominate in main-chain thermotropes that incorporate significant chain flexibility. Since the flow aligning regime has received little attention in previous attempts to model the rheology of textured, polydomain LCPs, we attempt to determine whether available models are capable of predicting the orientation and stress response of this class of LCP. We first examine the predictions of the polydomain Ericksen model, an adaptation of Ericksen's transversely isotropic fluid model which accounts for the polydomain distribution of director orientation while neglecting distortional elasticity. This simple model captures a number of qualitative and quantitative features associated with the evolution of orientation and stress during shear flow inception, but cannot cope with reversing flows. To consider the possible role of distortional elasticity in the re-orientation dynamics upon reversal, we evaluate the mesoscopically averaged domain theory of Larson and Doi [Larson and Doi (1991)], which incorporates a phenomenological description of distortional elastic effects. To date, their approach to account for polydomain structure has only been applied to describe tumbling LCPs. We find that it captures the qualitative transient orientation response to flow reversals, but is less successful in describing the evolution of stresses. This is linked to the decoupling approximation adopted during the model's development. Finally, a modified polydomain Ericksen model is introduced

  20. The orientation-enhancing effect of diphenyl aluminium phosphate nanorods in a liquid-crystalline epoxy matrix ordered by magnetic field

    Czech Academy of Sciences Publication Activity Database

    Mossety-Leszczak, B.; Strachota, Beata; Strachota, Adam; Steinhart, Miloš; Šlouf, Miroslav

    2015-01-01

    Roč. 72, November (2015), s. 238-255. ISSN 0014-3057 Institutional support: RVO:61389013 Keywords : liquid-crystalline epoxy resins * magnetic field orientation * nanocomposites Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.005, year: 2014

  1. Selectively deuterated liquid crystalline cyanoazobenzene side-chain polyesters. 3. Investigations of laser induced segmental mobility by Fourier transform infrared spectroscopy

    DEFF Research Database (Denmark)

    Kulinna, Christian; Hvilsted, Søren; Hendann, Claudia;

    1998-01-01

    The laser-induced anisotropy in thin films of an extensive number of cyanoazobenzene sidechain liquid crystalline polytetradecanedioates, -dodecanedioates, and -adipates selectively deuterated at different positions have been investigated with polarized FTIR spectroscopy. The analysis of the...

  2. EFFECT OF SEQUENCE STRUCTURE ON THE THERMOTROPIC LIQUID CRYSTALLINE PROPERTIES OF POLYESTERAMIDES BASED ON DIMETHYLBENZIDINE, BISPHENOL-A AND p-TEREPHTHALYL CHLORIDE

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    A series of thermotropic liquid crystalline polyesteramides with different sequence structure based on dimethylbenzidine (DMBD), bisphenol-A(BPA) and pterephthalyl chloride (TPC) was synthesized by changing the feeding order of monomers in low temperature solution polycondensation system. By means of NMR and a computer program the sequence structure parameters were measured. The effect of sequence structure on liquid crystalline phase transition temperature of PEAs obtained was investigated.

  3. SYNTHESIS AND CHARACTERIZATION OF LIQUID CRYSTALLINE MULTI-BLOCK COPOLYMERS,POLY[1,6-BIS(4-OXYBENZOYL-OXY)HEXANE TEREPHTHALATE]-b-BISPHENOL A POLYCARBONATE

    Institute of Scientific and Technical Information of China (English)

    Hui-qing Zhang; Xiong-yan Zhao; De-shan Liu; Qi-xiang Zhou

    1999-01-01

    A series of liquid crystalline multi-block copolymers poly[1,6-bis(4-oxybenzoyl-oxy)hexane terephthalate]-b-bisphenol A polycarbonate (PHTH-6-b-PC) with different segment lengths were synthesized in tetrachloroethane by solution polycondensation in which hydroxyl terminated PC and acyl chloride terminated PHTH-6 were used. It is found that block copolymers with high molecular weight and welldefined structures were obtained. All the block copolymers exhibit a nematic liquid crystalline texture.

  4. A structurally diverse library of safe-by-design citrem-phospholipid lamellar and non-lamellar liquid crystalline nano-assemblies

    DEFF Research Database (Denmark)

    Mat Azmi, Intan Diana Binti; Wibroe, Peter P; Wu, Lin-Ping;

    2016-01-01

    Non-lamellar liquid crystalline aqueous nanodispersions, known also as ISAsomes (internally self-assembled 'somes' or nanoparticles), are gaining increasing interest in drug solubilisation and bio-imaging, but they often exhibit poor hemocompatibility and induce cytotoxicity. This limits their ap......Non-lamellar liquid crystalline aqueous nanodispersions, known also as ISAsomes (internally self-assembled 'somes' or nanoparticles), are gaining increasing interest in drug solubilisation and bio-imaging, but they often exhibit poor hemocompatibility and induce cytotoxicity. This limits...

  5. Liquid crystalline polymers IX Main chain thermotropic poly (azomethine – ethers containing thiazole moiety linked with polymethylene spacers

    Directory of Open Access Journals (Sweden)

    2007-04-01

    Full Text Available A new homologous series of thermally stable thermotropic liquid crystalline poly(azomethine-ethers based on thiazole moiety were synthesized by solution polycondensation of 4,4`-diformyl-α,ω-diphenoxyalkanes, I–IV or 4,4`-diformyl-2,2`-dimethoxy-α,ω-diphenoxyalkanes V–VIII with the new bis(2-aminothiazole monomer X. A model compound XI was synthesized from X with benzaldehyde and characterized by elemental and spectral analyses. The inherent viscosities of the resulting polymers were in the range 0.43–1.34 dI/g. All the poly(azomethine-ethers were insoluble in common organic solvents but dissolved completely in concentrated H2SO4 and formic acid. The mesomorphic properties of these polymers were studied as a function of the diphenoxyalkane space length. Their thermotropic liquid crystalline properties were examined by DSC and optical polarizing microscopy and demonstrated that the resulting polymers form nematic mesophases over wide temperature ranges. The thermogravimetric analyses of those polymers were evaluated by TGA and DSC measurements and correlated to their structural units. X-ray analysis showed that polymers having some degree of crystallinity in the region 2θ = 5–60°. In addition, the morphological properties of selected examples were tested by scanning electron microscopy.

  6. Combinatorial approach for the rapid determination of thermochromic behavior of binary and ternary cholesteric liquid crystalline mixtures.

    Science.gov (United States)

    van der Werff, Louise C; Robinson, Andrea J; Kyratzis, Ilias L

    2012-11-12

    A combinatorial approach was developed for the rapid determination of thermochromic behavior of a large number of binary and ternary sterol based thermochromic liquid crystalline formulations. A binary mixture containing cholesteryl oleyl carbonate and cholesteryl nonanoate, and ternary mixtures also containing a third component, either cholesteryl oleate, cholesteryl benzoate, cholesteryl 2,4-dichlorobenzoate or cholesteryl propionate, were formulated via solvent deposition into a black Teflon coated aluminum 96 well plate. The temperature of the well plate was then varied, and the color appearance of the deposited mixture in each well was recorded. This approach allowed expedient examination of the thermochromic behavior for a large range of liquid crystal formulations. The accuracy of the rapid combinatorial technique was validated on selected thermochromic liquid crystal mixture compositions by comparing well thermochromic output with that observed using UV-vis spectroscopy on material produced in gram quantities. PMID:23072483

  7. Topology-mediated electro-optical behaviour of a wide-temperature liquid crystalline amorphous blue phase.

    Science.gov (United States)

    Kim, Min Su; Chien, Liang-Chy

    2015-10-28

    A wide-temperature liquid crystalline amorphous blue phase based on polymer network stabilization exhibits high thermodynamic stability with an extended temperature ranging from a few °C to more than 80 °C (including room temperature). Analyses using confocal laser scanning microscopy show that the polymer network imitates the aperiodic disclination-entangled structure of an amorphous blue phase and involves a highly intertwined interaction with liquid crystal molecules. The stabilized amorphous blue phase manifests a tens of microseconds response time, a consistent achromatic dark state and it is intrinsically hysteresis-free during the application of an electric field. The topological and electro-optical features of the stabilized amorphous blue phase are further compared with the stabilized isotropic and cubic blue phases. These results not only provide a physical perspective on the electro-optical response of a liquid crystal and polymer composite but also open up a new direction for electro-optical device applications. PMID:26329894

  8. Induction of thermotropic bicontinuous cubic phases in liquid-crystalline ammonium and phosphonium salts.

    Science.gov (United States)

    Ichikawa, Takahiro; Yoshio, Masafumi; Hamasaki, Atsushi; Taguchi, Satomi; Liu, Feng; Zeng, Xiang-bing; Ungar, Goran; Ohno, Hiroyuki; Kato, Takashi

    2012-02-01

    Two series of wedge-shaped onium salts, one ammonium and the other phosphonium, having 3,4,5-tris(alkyloxy)benzyl moieties, exhibit thermotropic bicontinuous "gyroid" cubic (Cub(bi)) and hexagonal columnar liquid-crystalline (LC) phases by nanosegregation between ionophilic and ionophobic parts. The alkyl chain lengths on the cationic moieties, anion species, and alkyl chain lengths on the benzyl moieties have crucial effects on their thermotropic phase behavior. For example, triethyl-[3,4,5-tris(dodecyloxy)benzyl]ammonium hexafluorophosphate forms the thermotropic Ia3d Cub(bi) LC phase, whereas an analogous compound with trifluoromethanesulfonate anion shows no LC properties. Synchrotron small-angle diffraction intensities from the Ia3d Cub(bi) LC materials provide electron density maps in the bulk state. The resulting maps show convincingly that the Ia3d Cub(bi) structure is composed of three-dimensionally interconnected ion nanochannel networks surrounded by aliphatic domains. A novel differential mapping technique has been applied successfully. The map of triethyl-[3,4,5-tris(decyloxy)benzyl]ammonium tetrafluoroborate has been subtracted from that of the analogous ammonium salt with hexafluorophosphate anion in the Ia3d Cub(bi) phases. The differential map shows that the counteranions are located in the core of the three-dimensionally interconnected nanochannel networks. Changing from trimethyl- via triethyl- to tripropylammonium cation changes the phase from columnar to Cub(bi) to no mesophase, respectively. This sensitivity to the widened shape for the narrow end of the molecule is explained successfully by the previously proposed semiquantitative geometric model based on the radial distribution of volume in wedge-shaped molecules. The LC onium salts dissolve lithium tetrafluoroborate without losing the Ia3d Cub(bi) LC phase. The Cub(bi) LC materials exhibit efficient ion-transporting behavior as a result of their 3D interconnected ion nanochannel networks

  9. Modulatory Effect of Human Plasma on the Internal Nanostructure and Size Characteristics of Liquid-Crystalline Nanocarriers

    DEFF Research Database (Denmark)

    Mat Azmi, Intan Diana Binti; Wu, Linping; Wibroe, Peter Popp;

    2015-01-01

    biphasic phase (a bicontinuous cubic phase with symmetry Pn3m coexisting with an inverted-type hexagonal (H2) phase) to a neat hexagonal (H2) phase, which decreases the median particle size. These observations were independent of a direct effect by serum albumin and dispersion-mediated complement......The inverted-type liquid-crystalline dispersions comprising cubosomes and hexosomes hold much potential for drug solubilization and site-specific targeting on intravenous administration. Limited information, however, is available on the influence of plasma components on nanostructural and...... the plasma complement system) on the integrity of the internal nanostructure, morphology, and fluctuation in size distribution of phytantriol (PHYT)-based nonlamellar crystalline dispersions. The results indicate that in the presence of plasma the internal nanostructure undergoes a transition from the...

  10. Influence of growth parameters on the surface morphology and crystallinity of InSb epilayers grown by liquid phase epitaxy

    Indian Academy of Sciences (India)

    N K Udayashankar; H L Bhat

    2003-12-01

    Unintentionally doped homoepitaxial InSb films have been grown by liquid phase epitaxy employing ramp cooling and step cooling growth modes. The effect of growth temperature, degree of supercooling and growth duration on the surface morphology and crystallinity were investigated. The major surface features of the grown film like terracing, inclusions, meniscus lines, etc are presented step-by-step and a variety of methods devised to overcome such undesirable features are described in sufficient detail. The optimization of growth parameters have led to the growth of smooth and continuous films. From the detailed morphological, X-ray diffraction, scanning electron microscopic and Raman studies, a correlation between the surface morphology and crystallinity has been established.

  11. THERMAL DEGRADATION OF THERMOTROPIC LIQUID CRYSTALLINE TERPOLYESTERS BASED ON VANILLIC ACID, p-HYDROXYBENZOIC ACID AND POLY(ETHYLENE TEREPHTHALATE)

    Institute of Scientific and Technical Information of China (English)

    LI Xingui; HUANG Meirong; GUAN Guihe; SUN Tong

    1993-01-01

    Nine thermotropic liquid crystalline terpolyesters based on vanillic acid(V), p-hydroxybenzoic acid(H) and poly(ethylene terephthalate)(E) were investigated by thermogravimetry to ascertain their thermostability and the kinetic parameters for thermal degradation. Overall activation energy data of the degradation had been calculated over the range 5~70% weight loss. The temperatures and the activation energy of the degradation lie in the ranges of 384~394 ℃ at a heating rate of 1 ℃/min and 176~205 KJ/mol at the weight loss of 5%, respectively, which suggests that the terpolyesters have good thermostability.

  12. Tilted Orientation of Photochromic Dyes with Guest-Host Effect of Liquid Crystalline Polymer Matrix for Electrical UV Sensing

    Science.gov (United States)

    Ranjkesh, Amid; Park, Min-Kyu; Park, Do Hyuk; Park, Ji-Sub; Choi, Jun-Chan; Kim, Sung-Hoon; Kim, Hak-Rin

    2015-01-01

    We propose a highly oriented photochromic dye film for an ultraviolet (UV)-sensing layer, where spirooxazine (SO) derivatives are aligned with the liquid crystalline UV-curable reactive mesogens (RM) using a guest-host effect. For effective electrical UV sensing with a simple metal-insulator-metal structure, our results show that the UV-induced switchable dipole moment amount of the SO derivatives is high; however, their tilting orientation should be controlled. Compared to the dielectric layer with the nearly planar SO dye orientation, the photochromic dielectric layer with the moderately tilted dye orientation shows more than seven times higher the UV-induced capacitance variation. PMID:26729116

  13. Preparation and Characterization of Liquid Crystalline Polyurethane/Al2O3/Epoxy Resin Composites for Electronic Packaging

    Directory of Open Access Journals (Sweden)

    Shaorong Lu

    2012-01-01

    Full Text Available Liquid crystalline polyurethane (LCPU/Al2O3/epoxy resin composites were prepared by using LCPU as modifier. The mechanical properties, thermal stability, and electrical properties of the LCPU/Al2O3/epoxy resin composites were investigated systematically. The thermal oxidation analysis indicated that LCPU/Al2O3/epoxy resin composites can sustain higher thermal decomposition temperature. Meanwhile, coefficient of thermal expansion (CTE was also found to decrease with addition of LCPU and nano-Al2O3.

  14. Synthesis of Isothianaphthene (ITN and 3,4-Ethylenedioxy-Thiophene (EDOT-Based Low-Bandgap Liquid Crystalline Conjugated Polymers

    Directory of Open Access Journals (Sweden)

    Hiromasa Goto

    2013-05-01

    Full Text Available Copolymers, consisting of isothianaphthene and phenylene derivatives with liquid crystal groups, were synthesized via Migita-Kosugi-Stille polycondensation reaction. IR absorption, UV-vis optical absorption, and PL spectroscopy measurements were carried out. Thermotropic liquid crystallinity of the polymers with bandgap of ~2.5 eV was confirmed.

  15. Rheology of the lamellar liquid-crystalline phase in polyethoxylated alcohol/water/heptane systems.

    Directory of Open Access Journals (Sweden)

    Gallegos, C.

    2005-06-01

    Full Text Available Linear viscoelastic tests as well as transient and steady flow experiments were carried out on lamellar liquid crystalline samples of poly (oxyethylene alcohol/water/heptane systems. The effect of surfactant and heptane concentrations on the rheological properties of the lamellar mesophase was investigated. The mechanical spectrum inside the linear viscoelastic regime shows, in all cases, a well-developed plateau region in the whole frequency range studied. The values of the dynamic functions were higher for intermediate surfactant or heptane concentrations indicative of a major development of the elastic network in the midrange of existence of the lamellar phase. Transient and steady flow experiments point out a shear-induced evolution of the lamellar microstructure. Different power law regions with different values of the flow index were detected in the viscosity versus shear rate plots. These shear-induced structural modifications were confirmed by using polarizing microscopy in an optical shearing cell. Structural modifications appear to be highly influenced by shear rate. In general, applying relatively high constant shear rates, the alignment of the bilayers followed by the appearance of the “oily streaks” structure was observed. Appearance of shear-induced vesicles occurs at high heptane content, as indicates the texture of close-packed monodisperse spherulites detected by polarizing microscopy.n este trabajo se han estudiado las propiedades reológicas de una fase líquido-cristalina laminar contenida en un sistema alcohol polietoxilado/agua/heptano, mediante ensayos viscoelásticos lineales, estacionarios y transitorios. El efecto de distintas variables como la composición de tensioactivo y heptano sobre dichas propiedades reológicas ha sido analizado. El espectro mecánico obtenido de la fase laminar muestra en todos los casos una región “plateau” en el intervalo de frecuencias estudiado así como mayores valores

  16. Thermal Properties and Crystallite Morphology of Nylon 66 Modified with a Novel Biphenyl Aromatic Liquid Crystalline Epoxy Resin

    Directory of Open Access Journals (Sweden)

    Xiufang Wen

    2013-10-01

    Full Text Available In order to improve the thermal properties of important engineering plastics, a novel kind of liquid crystalline epoxy resin (LCER, 3,3',5,5' -Tetramethylbiphenyl-4,4' -diyl bis(4-(oxiran-2-ylmethoxybenzoate (M1 was introduced to blend with nylon 66 (M2 at high temperature. The effects of M1 on chemical modification and crystallite morphology of M2 were investigated by rheometry, thermo gravimetric analysis (TGA, dynamic differential scanning calorimetry (DSC and polarized optical microscopy (POM. TGA results showed that the initial decomposition temperature of M2 increased by about 8 °C by adding 7% wt M1, indicating the improvement of thermal stability. DSC results illustrated that the melting point of composites decreased by 12 °C compared to M2 as the content of M1 increased, showing the improvement of processing property. POM measurements confirmed that dimension of nylon-66 spherulites and crystallization region decreased because of the addition of liquid crystalline epoxy M1.

  17. Magnetic Field Alignment of PS-P4VP: a Non-Liquid Crystalline Coil-Coil Block Copolymer

    Science.gov (United States)

    Rokhlenko, Yekaterina; Zhang, Kai; Larson, Steven; Gopalan, Padma; O'Hern, Corey; Osuji, Chinedum

    2015-03-01

    Magnetic fields provide the ability to control alignment of self-assembled soft materials such as block copolymers. Most prior work in this area has relied on the presence of ordered assemblies of anisotropic liquid crystalline species to ensure sufficient magnetic anisotropy to drive alignment. Recent experiments with poly(styrene-b-4-vinylpyridine), a non-liquid crystalline BCP, however, show field-induced alignment of a lamellar microstructure during cooling across the order-disorder transition. Using in situ x-ray scattering, we examine the roles of field strength and cooling rate on the alignment response of this low MW coil-coil BCP. Alignment is first observed at field strengths as low as 1 Tesla and improves markedly with both increasing field strength and slower cooling. We present a geometric argument to illustrate the origin of a finite, non-trivial magnetic susceptibility anisotropy for highly stretched surface-tethered polymer chains and corroborate this using coarse-grained molecular dynamics simulations. We rationalize the magnetic field response of the system in terms of the mobility afforded by the absence of entanglements, the intrinsic anisotropy resulting from the stretched polymer chains and sterically constrained conjugated rings, and the large grain size in these low molecular weight materials.

  18. Design and Characterization of a Novel p1025 Peptide-Loaded Liquid Crystalline System for the Treatment of Dental Caries

    Directory of Open Access Journals (Sweden)

    Giovana Maria Fioramonti Calixto

    2016-01-01

    Full Text Available Dental caries, mainly caused by the adhesion of Streptococcus mutans to pellicle-coated tooth surfaces, is an important public health problem worldwide. A synthetic peptide (p1025 corresponding to residues 1025–1044 of the adhesin can inhibit this binding. Peptides are particularly susceptible to the biological environment; therefore, a p1025 peptide-loaded liquid crystalline system (LCS consisting of tea tree oil as the oil phase, polyoxypropylene-(5-polyoxyethylene-(20-cetyl alcohol as the surfactant, and water or 0.5% polycarbophil polymer dispersions as the aqueous phase was employed as a drug delivery platform. This system exhibited anticaries and bioadhesive properties and provided a protective environment to p1025 at the site of action, thereby modulating its action, prolonging its contact with the teeth, and decreasing the frequency of administration. LCSs were characterized by polarized light microscopy (PLM, small-angle X-ray scattering (SAXS, and rheological, texture, and bioadhesive tests. PLM and SAXS revealed the presence of hexagonal liquid crystalline phases and microemulsions. Rheological analyses demonstrated that the addition of polymer dispersions favored characteristics such as shear thinning and thixotropy, hence improving buccal application. Bioadhesion tests showed that polymer dispersions contributed to the adhesion onto the teeth. Taken together, LCS could provide a novel pharmaceutical nanotechnology platform for dental caries treatment.

  19. SYNTHESIS OF LIQUID CRYSTALLINE COPOLYESTERS WITH T-SHAPED TWO-DIMENSIONAL MESOGENIC UNIT AND CROWN ETHER CYCLE

    Institute of Scientific and Technical Information of China (English)

    Shu-yuan Zhang; Xiao-jing Zhang; Gao-ming Mo; Zi-fa Li

    2008-01-01

    A novel series of liquid crystalline copolyesters with T-shaped two-dimensional mesogenic unit and crownether cycle of cis-4,4'-bis(4-hydroxyphenylazo)dibenzo-18-crown-6 was prepared via solution condensation polymerizationfrom 4,4'-(α,ω-hexanedioyloxy)dibenzoyl dichloride (M1), 2-(4'-ethoxyphenyl)hydroquinone (M2) and cis-4,4'-his(4-hydroxyphenylazo)dibenzo-18-crown-6 (M3). The molecular weights of copolyesters are not high, and the intrinsic viscosity[η] of copolyesters ranges from 0.29-0.43. The monomers' structures were identified by elemental analysis, IR, UV,1H-NMR, MS, etc. All the copolyesters are yellowish powders and insoluble in THF and CHCl3 at room temperature exceptCP-9. The properties of copolyesters were investigated by using GPC, [η], DSC, TG.WAXD and POM. It was found that allthe copolyesters entered into liquid crystalline phase when they were heated to above their melting temperature (Tm). Thethreaded texture and schlieren texture of nematic phase can be observed on POM. Their Tm and isotropic temperature (Ti)decrease gradually, while thermal stability increase with varying the content of T-shaped two-dimensional mesogenic unit inthe copolyesters.

  20. Current Advances in the Carbon Nanotube/Thermotropic Main-Chain Liquid Crystalline Polymer Nanocomposites and Their Blends

    Directory of Open Access Journals (Sweden)

    Lin Li

    2012-03-01

    Full Text Available Because of their extraordinary properties, such as high thermal stability, flame retardant, high chemical resistance and high mechanical strength, thermotropic liquid crystalline polymers (TLCPs have recently gained more attention while being useful for many applications which require chemical inertness and high strength. Due to the recent advance in nanotechnology, TLCPs are usually compounded with nanoparticles to form particulate composites to enhance their properties, such as barrier properties, electrical properties, mechanical properties and thermal properties. Carbon-based nanofillers such as carbon nanotube (CNT, graphene and graphene oxide are the most common fillers used for the TLCP matrices. In this review, we focus on recent advances in thermotropic main-chain liquid crystalline polymer nanocomposites incorporated with CNTs. However, the biggest challenges in the preparation of CNT/TLCP nanocomposites have been shown to be inherent in the dispersion of CNTs into the TLCP matrix, the alignment and control of CNTs in the TLCP matrix and the load-transfer between the TLCP matrix and CNTs. As a result, this paper reviews recent advances in CNT/TLCP nanocomposites through enhanced dispersion of CNTs in TLCPs as well as their improved interfacial adhesion with the TLCP matrices. Case studies on the important role of chemically modified CNTs in the TLCP/thermoplastic polymer blends are also included.

  1. Analysis of the minority crystalline phases in bulk superconducting MgB2 obtained by reactive liquid Mg infiltration

    International Nuclear Information System (INIS)

    The preparation of MgB2 starting from the elements (in situ process), when performed in conjunction with the Mg liquid infiltration process, gives rise to very high dense manufacts, with outstanding mechanical and superconducting characteristics. The infiltration technique is particularly suitable when realized into preforms of crystalline boron powders of grain size up to about 100 μm; however, the resulting products typically present a microstructure characterized by a composite morphology, indicating a inhomogeneous distribution of different crystalline phases. In this paper the composition and the morphology of typical products has been analyzed with several techniques, including X-ray powder diffraction (XRPD), scanning electron microscopy and X-ray fluorescence microanalysis, aiming to quantify the (spatial) distribution of crystalline phases and the presence of minority phases different from the MgB2. The minority phases that are commonly present in the MgB2 infiltration preparation are residual elemental magnesium and a new boron-rich magnesium boride phase (Mg2B25), recently discovered and structurally characterized (by unconventional XRPD methods) by our group. We have analyzed the common morphological features of typical MgB2 samples, and cross-checked the analytical results obtained from different experimental techniques. Our results show that the new Mg2B25 phase amounts to less than 10 molar % of the MgB2 entire product, and that it is mainly concentrated, as submicronic inclusions (inside the larger crystalline MgB2 grains) where it can reach concentration values up to 40 molar %

  2. Quasi-liquid crystalline materials with special electro-optic properties

    Science.gov (United States)

    Krongauz, Valeri

    1988-12-01

    Photo/thermochromic liquid crystals and liquid crystal polymers were synthesized by combination of spiropyran and mesogenic groups in one low molar mass molecule or macromolecules. The spiropyran-merocyanine conversion affects the mesophase structure and results in formation of non-centrosymmetric nonlinear optical material, generating second harmonics. Aggregation of merocyanine molecules leads to a new photomechanical effect in low molar mass compounds and to the rheo-optical and boundary spectral effects in the side chain liquid crystal copolymers containing spiropyran side groups. Polychromic phototransformations in the copolymers as well as accompanying structural changes enable use of the polymer films for optical information storage.

  3. NATO Advanced Research Workshop on Computational Methods for Polymers and Liquid Crystalline Polymers

    CERN Document Server

    Pasini, Paolo; Žumer, Slobodan; Computer Simulations of Liquid Crystals and Polymers

    2005-01-01

    Liquid crystals, polymers and polymer liquid crystals are soft condensed matter systems of major technological and scientific interest. An understanding of the macroscopic properties of these complex systems and of their many and interesting peculiarities at the molecular level can nowadays only be attained using computer simulations and statistical mechanical theories. Both in the Liquid Crystal and Polymer fields a considerable amount of simulation work has been done in the last few years with various classes of models at different special resolutions, ranging from atomistic to molecular and coarse-grained lattice models. Each of the two fields has developed its own set of tools and specialized procedures and the book aims to provide a state of the art review of the computer simulation studies of polymers and liquid crystals. This is of great importance in view of a potential cross-fertilization between these connected areas which is particularly apparent for a number of experimental systems like, e.g. poly...

  4. [BMIM] [BF4] ionic liquid assistance effect on the crystallinity and morphology of Sb2S3 nanostructures synthesized by ultrasound

    International Nuclear Information System (INIS)

    Unidimensional crystalline Sb2S3 nanostructures were successfully synthesized by ultrasound irradiation assisted with the ionic liquid 1-n-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF4]. The starting reagents were SbCl3, thioacetamide, absolute ethanol (AET), and the used ionic liquid was [BMIM][BF4]. The resultant materials were thermally annealed at 155 and 200 oC under controlled vacuum conditions. The experiments showed that IL assistance played a key role in the crystallinity and morphology of the obtained products. The resultant materials were characterized by powder X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray analysis (EDX). (author).

  5. Comparison of drug release from liquid crystalline monoolein dispersions and solid lipid nanoparticles using a flow cytometric technique

    Directory of Open Access Journals (Sweden)

    Mohamed Z. Dawoud

    2016-03-01

    Full Text Available Colloidal lipid particles such as solid lipid nanoparticles and liquid crystalline nanoparticles have great opportunities as drug carriers especially for lipophilic drugs intended for intravenous administration. In order to evaluate drug release from these nanoparticles and determine their behavior after administration, emulsion droplets were used as a lipophilic compartment to which the transfer of a model drug was measured. The detection of the model drug transferred from monoolein cubic particles and trimyristin solid lipid nanoparticles into emulsion droplets was performed using a flow cytometric technique. A higher rate and amount of porphyrin transfer from the solid lipid nanoparticles compared to the monoolein cubic particles was observed. This difference might be attributed to the formation of a highly ordered particle which leads to the expulsion of drug to the surface of the crystalline particle. Furthermore, the sponge-like structure of the monoolein cubic particles decreases the rate and amount of drug transferred. In conclusion, the flow cytometric technique is a suitable technique to study drug transfer from these carriers to large lipophilic acceptors. Monoolein cubic particles with their unique structure can be used successfully as a drug carrier with slow drug release compared with trimyristin nanoparticles.

  6. PREPARATION OF LIQUID CRYSTALLINE COPOLYESTERS WITH SPACERS BASED ON BISPHENOL- A,BISPHENOL- S OR POLYSULFONE BY DIRECT POLYCONDENSATION

    Institute of Scientific and Technical Information of China (English)

    WANG Pingping; ZHANG Hongzhi

    1989-01-01

    Four series of copolyesters were synthesized by direct polycondensation reaction between aromatic dicarboxylic acids and bisphenols by using tosyl chloride and N, N-dimethylformamide ( DMF ) in pyridine under mild conditions. The electron-rich hydroxyl groups of bisphenols favoured the polycondensation reaction and the order of relative reactivities of bisphenols is as follow:bisphenol-A > hydroquinone ~ bisphenol-S > chlorohydroquinone .Themesomorphic properties of copolyesters were examined by birefringence under polarizing microscope, melt transparency, DSC and X-ray diffraction . The minimum molar fraction of mesogenic units needed for the appearance of liquid crystallinity is not higher than 0.1 despite of the different varieties and lengths of the spacers studied.

  7. Making and Remaking Dynamic 3D Structures by Shining Light on Flat Liquid Crystalline Vitrimer Films without a Mold.

    Science.gov (United States)

    Yang, Yang; Pei, Zhiqiang; Li, Zhen; Wei, Yen; Ji, Yan

    2016-02-24

    Making dynamic three-dimensional (3D) structures capable of reversible shape changes or locomotion purely out of dry polymers is very difficult. Meanwhile, no previous dynamic 3D structures can be remade into new configurations while being resilient to mechanical damages and low temperature. Here, we show that light-activated transesterification in carbon nanotube dispersed liquid crystalline vitrimers enables flexible design and easy building of dynamic 3D structures out of flat films upon irradiation of light without screws, glues, or molds. Shining light also enables dynamic 3D structures to be quickly modified on demand, restored from distortion, repaired if broken, in situ healed when microcrack appears, assembled for more sophisticated structures, reconfigured, and recycled after use. Furthermore, the fabrication, reconfiguration, actuation, reparation, and assembly as well as healing can be performed even at extremely low temperatures (e.g., -130 °C). PMID:26840838

  8. Enhanced thermal and mechanical properties of epoxy composites by mixing thermotropic liquid crystalline epoxy grafted graphene oxide

    Directory of Open Access Journals (Sweden)

    B. Qi

    2014-07-01

    Full Text Available Graphene oxide (GO sheets were chemically grafted with thermotropic liquid crystalline epoxy (TLCP. Then we fabricated composites using TLCP-g-GO as reinforcing filler. The mechanical properties and thermal properties of composites were systematically investigated. It is found that the thermal and mechanical properties of the composites are enhanced effectively by the addition of fillers. For instance, the composites containing 1.0 wt% of TLCP-g-GO present impact strength of 51.43 kJ/m2, the tensile strength of composites increase from 55.43 to 80.85 MPa, the flexural modulus of the composites increase by more than 48%. Furthermore, the incorporation of fillers is effective to improve the glass transition temperature and thermal stability of the composites. Therefore, the presence of the TLCP-g-GO in the epoxy matrix could make epoxy not only stronger but also tougher.

  9. A review of immune amplification via ligand clustering by self-assembled liquid-crystalline DNA complexes.

    Science.gov (United States)

    Lee, Ernest Y; Lee, Calvin K; Schmidt, Nathan W; Jin, Fan; Lande, Roberto; Curk, Tine; Frenkel, Daan; Dobnikar, Jure; Gilliet, Michel; Wong, Gerard C L

    2016-06-01

    We examine how the interferon production of plasmacytoid dendritic cells is amplified by the self-assembly of liquid-crystalline antimicrobial peptide/DNA complexes. These specialized dendritic cells are important for host defense because they quickly release large quantities of type I interferons in response to infection. However, their aberrant activation is also correlated with autoimmune diseases such as psoriasis and lupus. In this review, we will describe how polyelectrolyte self-assembly and the statistical mechanics of multivalent interactions contribute to this process. In a more general compass, we provide an interesting conceptual corrective to the common notion in molecular biology of a dichotomy between specific interactions and non-specific interactions, and show examples where one can construct exquisitely specific interactions using non-specific interactions. PMID:26956527

  10. Graphene oxide-wrapped PEGylated liquid crystalline nanoparticles for effective chemo-photothermal therapy of metastatic prostate cancer cells.

    Science.gov (United States)

    Thapa, Raj Kumar; Youn, Yu Seok; Jeong, Jee-Heon; Choi, Han-Gon; Yong, Chul Soon; Kim, Jong Oh

    2016-07-01

    Here, we report the preparation of PEGylated liquid crystalline nanoparticles (LCN) loaded with docetaxel (DTX) and wrapped with graphene oxide (GO), called PEG-GO/LCN/DTX, for effective chemo-photothermal therapy of metastatic prostate cancer cells. The prepared formulation exhibited a small particle size (prostate cancer cells and exhibited potent apoptotic and antimigration effects, mediated by the combination of the anticancer effects of DTX and the thermal heat induced by exposure of GO to NIR light. Taken together, our findings support that PEG-GO/LCN/DTX may be an effective system for treatment of metastatic prostate cancer. Moreover, the results establish a proof-of-concept for the potential chemo-photothermal functionality of PEG-GO/LCN/DTX. This hybrid system of LCN and GO could provide controlled and targeted drug delivery with enhanced NIR-induced thermal effects for effective treatment of metastatic cancers. PMID:27022866

  11. Rheological properties in discotic liquid crystalline phases of 2,3,7,8,12,13-hexa(n-tetradecanoyloxy)truxene.

    Science.gov (United States)

    Negita, Keishi; Kawano, Chiharu; Moriya, Keiichi

    2004-08-01

    Measurements of rheological properties, including the electrorheological effect, are made in liquid crystalline phases, discotic nematic (ND) and discotic disordered rectangular columnar (Drd) phases, of 2,3,7,8,12,13-hexa(n-tetradecanoyloxy)truxene. It is found that the fluidity of the ND phase is Newtonian and an application of high electric field perpendicular to the flow direction (velocity gradient direction) causes a decrease of the viscosity. These results indicate that a flow alignment of the director occurs with its orientation near the velocity gradient direction and the signs of the Leslie coefficients alpha2 and alpha3 are positive. From the temperature dependence of alpha2, instability of the flow alignment structure in ND and Drd phases is also discussed. PMID:15447504

  12. MORPHOLOGICAL STUDY ON THE ORIENTED CHITOSAN FILM OBTAINED FROM PRE-SHEARED LIQUID CRYSTALLINE SOLUTION IN DICHLOROACETIC ACID

    Institute of Scientific and Technical Information of China (English)

    Zhong-ming Hu; Li-heng Wu; Da-cheng Wu; Shou-xi Chen

    2001-01-01

    The oriented chitosan films obtained from pre-sheared liquid crystalline chitosan/dichloroacetic acid (DCA)solutions were studied by means of polarized optical microscopy (POM), scanning electron microscopy (SEM), infra-red dichroism technique and wide angle X-ray diffraction (WAXD). The shear induced band texture in the film was found to correspond to the sinusoidal fibrillar microstructure along the shearing direction on the basis of POM and SEM observations.The sinusoidal fibril was found to be lying within the film plane. The model of chitosan molecular orientation in the presheared film with band texture can be established assuming that the main chain orients in the shearing direction and the side group is perpendicular to the shearing direction. The WAXD azimuthal scanning at 2θ = 20° indicates that the (002) plane orients perpendicular to the shearing direction.``

  13. X-Ray Scattering Investigation of Molecular Orientation During Shear Flow in Model Thermotropic Liquid Crystalline Polymers

    Science.gov (United States)

    Ugaz, V. M.; Burghardt, W. R.

    1998-03-01

    We describe the use of in-situ x-ray scattering techniques to directly measure the influence of flow on molecular orientation in two different model thermotropic liquid crystalline polymers (LCPs). These model materials, one a polyester and the other a polyether, are both composed of rigid mesogens randomly copolymerized with flexible spacer chains of two different lengths. This architecture provides both LCPs with an accessible isotropic transition temperature, thereby allowing a well-defined thermal history to be established prior to application of shear flow. We present measurements of molecular orientation in steady shear flow, during relaxation after cessation of shear flow, and in the transient periods during shear flow inception and reversal. These results are then compared with corresponding rheological data, providing a unique opportunity to directly correlate structural and rheological behavior in each material as well as between materials.

  14. Thermotropic liquid crystalline polyesters derived from bis-(4-hydroxybenzoyloxy)-2-methyl-1,4-benzene and aliphatic dicarboxylic acid chlorides

    Indian Academy of Sciences (India)

    Khudbudin Mulani; Mohasin Momin; Nitin Ganjave; Nayaku Chavan

    2015-09-01

    A series of thermotropic liquid crystalline polyesters derived from bis-(4-hydroxybenzoyloxy)-2-methyl-1,4-benzene (BHBOMB) and aliphatic dicarboxylic acid chlorides were investigated. All these polyesters were synthesized by interfacial polycondensation method and characterized by differential scanning calorimetry and wide-angle X-ray diffractometer. These polyesters consist of BHBOMB as a mesogenic diol and aliphatic diacid chlorides were used as flexible spacers. The length of oligomethylene units in polymer was varied from the trimethylene to the dodecamethylene groups. The transition temperatures and thermodynamic properties were studied for all these polymers. All these polyesters were soluble in chlorinated solvents such as chloroform, dichloromethane, dichloroethane, etc. More importantly, all these polyesters exhibited very large mesophase stability.

  15. Solution-liquid-solid growth of crystalline III-V semiconductors: An anology to vapor-liquid-solid growth

    Energy Technology Data Exchange (ETDEWEB)

    Trentler, T.J.; Hickman, K.M.; Goel, S.C. [and others

    1995-12-15

    Until now, micrometer-scale or larger crystals of the III-V semiconductors have not been grown at low temperatures for lack of suitable crystallization mechanisms for highly covalent nonmolecular solids. A solution-liquid-solid mechanism for the growth of InP, InAs, and GaAs is described that uses simple, low-temperature ({le}203{degrees}C), solution-phase reactions. The materials are produced as polycrystalline fibers or near-single-crystal whiskers having widths of 10 to 150 nanometers and lengths of up to several micrometers. This mechanism shows that processes analogous to vapor-liquid-solid growth can operate at low temperatures; similar synthesis routes for other covalent solids may be possible. 26 refs., 7 figs.

  16. Entrapment of curcumin into monoolein-based liquid crystalline nanoparticle dispersion for enhancement of stability and anticancer activity

    Directory of Open Access Journals (Sweden)

    Baskaran R

    2014-06-01

    Full Text Available Rengarajan Baskaran,1 Thiagarajan Madheswaran,2 Pasupathi Sundaramoorthy,1 Hwan Mook Kim,1 Bong Kyu Yoo1 1College of Pharmacy, Gachon University, Incheon, South Korea; 2College of Pharmacy Yeungnam University, Gyeongsan, South Korea Abstract: Despite the promising anticancer potential of curcumin, its therapeutic application has been limited, owing to its poor solubility, bioavailability, and chemical fragility. Therefore, various formulation approaches have been attempted to address these problems. In this study, we entrapped curcumin into monoolein (MO-based liquid crystalline nanoparticles (LCNs and evaluated the physicochemical properties and anticancer activity of the LCN dispersion. The results revealed that particles in the curcumin-loaded LCN dispersion were discrete and monodispersed, and that the entrapment efficiency was almost 100%. The stability of curcumin in the dispersion was surprisingly enhanced (about 75% of the curcumin survived after 45 days of storage at 40°C, and the in vitro release of curcumin was sustained (10% or less over 15 days. Fluorescence-activated cell sorting (FACS analysis using a human colon cancer cell line (HCT116 exhibited 99.1% fluorescence gating for 5 µM curcumin-loaded LCN dispersion compared to 1.36% for the same concentration of the drug in dimethyl sulfoxide (DMSO, indicating markedly enhanced cellular uptake. Consistent with the enhanced cellular uptake of curcumin-loaded LCNs, anticancer activity and cell cycle studies demonstrated apoptosis induction when the cells were treated with the LCN dispersion; however, there was neither noticeable cell death nor significant changes in the cell cycle for the same concentration of the drug in DMSO. In conclusion, entrapping curcumin into MO-based LCNs may provide, in the future, a strategy for overcoming the hurdles associated with both the stability and cellular uptake issues of the drug in the treatment of various cancers. Keywords: liquid

  17. Liquid crystalline phase synthesis of nanoporous MnO2 thin film arrays as an electrode material for electrochemical capacitors

    International Nuclear Information System (INIS)

    Graphical abstract: Three-dimensional (3D) MnO2 thin film arrays with nanoporous structure is electrodeposited on Ti foil from hexagonal lyotropic liquid crystalline phase. Low-angle X-ray diffraction (XRD), wide-angle XRD, field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) are employed to study the morphology and the structure of the as-synthesized MnO2 materials. Galvanostatic charge/discharge measurements show the nanoporous, 3D electrode material exhibits excellent capacitive performance between the potential range of −0.1 to 0.9 V, and a maximum specific capacitance as high as 462 F g−1 are achieved in 0.5 M Na2SO4 solution at a charge/discharge current density of 4 A g−1. Highlights: ► 3D MnO2 thin film arrays with nanoporous structure is fabricated for the first time. ► A maximum specific capacitance as high as 462 F g−1 is obtained. ► The 3D and nanoporous superarchitecture facilitate electrolyte penetration. -- Abstract: Three-dimensional (3D) MnO2 thin film arrays with nanoporous structure is electrodeposited on Ti foil from hexagonal lyotropic liquid crystalline phase. Low-angle X-ray diffraction (XRD), wide-angle XRD, field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) are employed to study the morphology and the structure of the as-synthesized MnO2 materials. Galvanostatic charge/discharge measurements show the nanoporous, 3D electrode material exhibits excellent capacitive performance between the potential range of −0.1 to 0.9 V, and a maximum specific capacitance as high as 462 F g−1 are achieved in 0.5 M Na2SO4 solution at a charge/discharge current density of 4 A g−1.

  18. Alkane fluids confined and compressed by two smooth crystalline gold surfaces: Pure liquids and mixtures

    Science.gov (United States)

    Alvarez, Lina P. Merchan

    With the use of grand canonical molecular dynamics, we studied the slow compression(0.01m/s) of very thin liquid films made of equimolar mixtures of short and long alkane chains (hexane and hexadecane), and branched and unbranched alkanes (phytane and hexadecane). Besides comparing how these mixtures behave under constant speed compression, we will compare their properties with the behavior and structure of the pure systems undergoing the same type of slow compression. To understand the arrangement of the molecules inside the confinement, we present segmental and molecular density profiles, average length and orientation of the molecules inside well formed gaps. To observe the effects of the compression on the fluids, we present the number of confined molecules, the inlayer orientation, the solvation force and the inlayer diffusion coefficient, versus the thickness of the gap. We observe that pure hexadecane, although liquid at this temperature, starts presenting strong solid-like behavior when it is compressed to thicknesses under 30A, while pure hexane and pure phytane continue to behave liquid-like except at 13A when they show some weak solid-like features. When hexadecane is mixed with the short straight hexane, it remains liquid down to 28A at which point this mixture behaves solid-like with an enhanced alignment of the long molecules not seen in its pure form; but when hexade-cane is mixed with the branched phytane the system does not present the solid-like features seen when hexadecane is compressed pure.

  19. Molecular tilt near nanoparticles in the smectic A phase of de Vries liquid-crystalline compound

    Czech Academy of Sciences Publication Activity Database

    Lejček, Lubor; Novotná, Vladimíra; Glogarová, Milada

    2014-01-01

    Roč. 89, č. 1 (2014), "012505-1"-"012505-6". ISSN 1539-3755 R&D Projects: GA ČR(CZ) GAP204/11/0723 Institutional support: RVO:68378271 Keywords : liquid crystals * smectic phases * nanoparticles * deVries behaviour Subject RIV: JJ - Other Materials Impact factor: 2.288, year: 2014 http://pre.aps.org/abstract/PRE/v89/i1/e012505

  20. Unique effect of the electric field on a new liquid crystalline lactic acid derivative

    Czech Academy of Sciences Publication Activity Database

    Novotná, Vladimíra; Glogarová, Milada; Kašpar, Miroslav; Hamplová, Věra; Lejček, Lubor; Pociecha, D.

    2015-01-01

    Roč. 11, č. 23 (2015), s. 4649-4657. ISSN 1744-683X R&D Projects: GA ČR GA13-14133S; GA ČR(CZ) GA15-02986S Grant ostatní: AV ČR(CZ) M100101211 Institutional support: RVO:68378271 Keywords : liquid crystals * TGBA phase * Frederiks transition Subject RIV: JJ - Other Materials Impact factor: 4.029, year: 2014

  1. Effect of chiral photosensitive liquid crystalline dopants on theperformance of organic solar cells

    Czech Academy of Sciences Publication Activity Database

    Iwan, A.; Boharewicz, B.; Tazbir, I.; Hamplová, Věra; Bubnov, Alexej

    2015-01-01

    Roč. 104, Feb (2015), s. 53-60. ISSN 0038-1101 R&D Projects: GA MŠk 7AMB13PL041; GA ČR GA13-14133S; GA MŠk(CZ) LD14007 Grant ostatní: AVČR(CZ) M100101204 Institutional support: RVO:68378271 Keywords : organic solar cell * composite with liquid crystal Subject RIV: CG - Electrochemistry Impact factor: 1.504, year: 2014

  2. Low-temperature liquid precursors of crystalline metal oxides assisted by heterogeneous photocatalysis.

    Science.gov (United States)

    Bretos, Iñigo; Jiménez, Ricardo; Pérez-Mezcua, Dulce; Salazar, Norberto; Ricote, Jesús; Calzada, M Lourdes

    2015-04-24

    The photocatalytically assisted decomposition of liquid precursors of metal oxides incorporating TiO2 particles enables the preparation of functional layers from the ferroelectric Pb(Zr,Ti)O3 and multiferroic BiFeO3 perovskite systems at temperatures not exceeding 350 ºC. This enables direct deposition on flexible plastic, where the multifunctionality provided by these complex-oxide materials guarantees their potential use in next-generation flexible electronics. PMID:25776728

  3. A study of the selective reflection properties of some liquid crystalline cellulose derivatives

    International Nuclear Information System (INIS)

    Cellulose is a natural, versatile and biodegradable polymer, which like most natural polymers is chiral. Some cellulose derivatives form cholesteric liquid crystal phases either on heating or by the addition of a suitable solvent, giving rise to thermotropic and lyotropic liquid crystals respectively. Cholesteric cellulose derivatives selectively reflect circularly polarised light, which is centred at a wavelength, which corresponds to the pitchlength of the cholesteric phase. Some lyotropic cellulosic liquid crystal materials were identified and synthesised to explore possible methods to exploit cholesteric behaviour to produce films for potential use as reflective coatings. Films were prepared in one of two ways, either by casting from a lyotropic solution in a suitable organic solvent or by dissolving the material in a monomer, which could then be photopolymerised to form a composite reflective film. Since all cellulose derivatives share the same chiral backbone it might be expected that they will have the same chirality, however the nature of the substituents is responsible for determining the chirality of cellulosic derivatives which is not always the same as cellulose itself. (author)

  4. Nondisruptive Dissolution of Hyperpolarized (129) Xe into Viscous Aqueous and Organic Liquid Crystalline Environments.

    Science.gov (United States)

    Truxal, Ashley E; Slack, Clancy C; Gomes, Muller D; Vassiliou, Christophoros C; Wemmer, David E; Pines, Alexander

    2016-04-01

    Studies of hyperpolarized xenon-129 (hp-(129) Xe) in media such as liquid crystals and cell suspensions are in demand for applications ranging from biomedical imaging to materials engineering but have been hindered by the inability to bubble Xe through the desired media as a result of viscosity or perturbations caused by bubbles. Herein a device is reported that can be reliably used to dissolve hp-(129) Xe into viscous aqueous and organic samples without bubbling. This method is robust, requires small sample volumes (<60 μL), is compatible with existing NMR hardware, and is made from readily available materials. Experiments show that Xe can be introduced into viscous and aligned media without disrupting molecular order. We detected dissolved xenon in an aqueous liquid crystal that is disrupted by the shear forces of bubbling, and we observed liquid-crystal phase transitions in (MBBA). This tool allows an entirely new class of samples to be investigated by hyperpolarized-gas NMR spectroscopy. PMID:26954536

  5. Two-mode Ginzburg-Landau theory of crystalline anisotropy for fcc-liquid interfaces

    Science.gov (United States)

    Wu, Kuo-An; Lin, Shang-Chun; Karma, Alain

    2016-02-01

    We develop a Ginzburg-Landau (GL) theory for fcc crystal-melt systems at equilibrium by employing two sets of order parameters that correspond to amplitudes of density waves of principal reciprocal lattice vectors and amplitudes of density waves of a second set of reciprocal lattice vectors. The choice of the second set of reciprocal lattice vectors is constrained by the condition that this set must form closed triangles with the principal reciprocal lattice vectors in reciprocal space to make the fcc-liquid transition first order. The capillary anisotropy of fcc-liquid interfaces is investigated by GL theory with amplitudes of and density waves. Furthermore, we explore the dependence of the anisotropy of the excess free energy of the solid-liquid interface on density waves of higher-order reciprocal lattice vectors such as by extending the two-mode GL theory with an additional mode. The anisotropy calculated using GL theory with input parameters from molecular dynamics (MD) simulations for fcc Ni is compared to that measured in MD simulations.

  6. Molecular structure of the discotic liquid crystalline phase of hexa-peri-hexabenzocoronene/oligothiophene hybrid and their charge transport properties

    International Nuclear Information System (INIS)

    Using atomistic molecular dynamics simulation, we study the discotic columnar liquid crystalline (LC) phases formed by a new organic compound having hexa-peri-Hexabenzocoronene (HBC) core with six pendant oligothiophene units recently synthesized by Nan Hu et al. [Adv. Mater. 26, 2066 (2014)]. This HBC core based LC phase was shown to have electric field responsive behavior and has important applications in organic electronics. Our simulation results confirm the hexagonal arrangement of columnar LC phase with a lattice spacing consistent with that obtained from small angle X-ray diffraction data. We have also calculated various positional and orientational correlation functions to characterize the ordering of the molecules in the columnar arrangement. The molecules in a column are arranged with an average twist of 25° having an average inter-molecular separation of ∼5 Å. Interestingly, we find an overall tilt angle of 43° between the columnar axis and HBC core. We also simulate the charge transport through this columnar phase and report the numerical value of charge carrier mobility for this liquid crystal phase. The charge carrier mobility is strongly influenced by the twist angle and average spacing of the molecules in the column

  7. Molecular structure of the discotic liquid crystalline phase of hexa-peri-hexabenzocoronene/oligothiophene hybrid and their charge transport properties

    Energy Technology Data Exchange (ETDEWEB)

    Bag, Saientan; Maingi, Vishal; Maiti, Prabal K., E-mail: maiti@physics.iisc.ernet.in [Department of Physics, Center for Condensed Matter Theory, Indian Institute of Science, Bangalore 560012 (India); Yelk, Joe; Glaser, Matthew A.; Clark, Noel A. [Department of Physics, University of Colorado, Boulder, Colorado 80309 (United States); Walba, David M. [Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309 (United States)

    2015-10-14

    Using atomistic molecular dynamics simulation, we study the discotic columnar liquid crystalline (LC) phases formed by a new organic compound having hexa-peri-Hexabenzocoronene (HBC) core with six pendant oligothiophene units recently synthesized by Nan Hu et al. [Adv. Mater. 26, 2066 (2014)]. This HBC core based LC phase was shown to have electric field responsive behavior and has important applications in organic electronics. Our simulation results confirm the hexagonal arrangement of columnar LC phase with a lattice spacing consistent with that obtained from small angle X-ray diffraction data. We have also calculated various positional and orientational correlation functions to characterize the ordering of the molecules in the columnar arrangement. The molecules in a column are arranged with an average twist of 25° having an average inter-molecular separation of ∼5 Å. Interestingly, we find an overall tilt angle of 43° between the columnar axis and HBC core. We also simulate the charge transport through this columnar phase and report the numerical value of charge carrier mobility for this liquid crystal phase. The charge carrier mobility is strongly influenced by the twist angle and average spacing of the molecules in the column.

  8. Development of liquid-crystalline epoxy resin containing ester mesogen%酯基液晶环氧树脂研究进展

    Institute of Scientific and Technical Information of China (English)

    徐淑权; 李玲; 王晓铭

    2013-01-01

    介绍了酯基液晶环氧树脂的合成方法及其优缺点,介晶基元的长度、取代基以及柔性间隔链对酯基液晶环氧树脂液晶性能的影响,固化剂的选择、固化温度和酯基液晶环氧树脂的化学结构对酯基液晶环氧树脂固化特性的影响,并展望了酯基液晶环氧树脂的发展前景.%The synthesis methods of liquid-crystalline epoxy resin containing ester mesogen and their advantages and disadvantages are introduced in this paper. The influences of the length of the mesogenic unit, substituents and flexible spacer on the performance of the liquid-crystalline epoxy resin containing ester mesogen are analyzed. The effects of curing agent choice, curing temperature and chemical structure of the liquid-crystalline epoxy resin containing ester mesogen on the curing characteristics studied as well. The prospects of liquid-crystalline epoxy resin containing ester mesogen are proposed.

  9. Hydrodynamic theories for mixtures of polymers and rodlike liquid crystalline polymers.

    Science.gov (United States)

    Forest, M Gregory; Wang, Qi

    2005-10-01

    We develop a hydrodynamic theory for flows of incompressible blends of flexible polymers and rodlike nematic polymers (RNPs) or rodlike nematic liquid crystal polymers (RNLCPs) extending the thermodynamical theory of Muratov and E [J. Chem. Phys. 116, 4723 (2002)] for phase separation kinetics of the blend. We model the flexible polymer molecules in the polymer matrix as Rouse chains and assume the translational diffusion of the molecules is predominantly through the volume fraction of the flexible polymer and the molecules of rodlike nematic liquid crystal polymers. We then (i) derive the translational flux for the rodlike nematic liquid crystal polymers to ensure the incompressibility constraint; (ii) derive the elastic stress tensor, accounting for the contribution from both the rodlike nematic polymer and the flexible polymer matrix, as well as the extra elastic body force due to the nonlocal intermolecular potential for long range molecular interaction; (iii) show that the theory obeys positive entropy production and thereby satisfies the second law of thermodynamics. By applying the gradient expansion technique on the number density function of RNLCPs, we present an approximate, weakly nonlocal theory in differential form in which the intermolecular potential is given by gradients of the number density function of the RNLCP and the volume fraction of the flexible polymer. In the approximate theory, the elastic stress is augmented by an extra stress tensor due to the spatial convection of the macroscopic material point and long range interaction, whose divergence yields the analogous extra elastic body force with respect to the nonlocal intermolecular potential. Finally, we compare the model in steady simple shear with the Doi theory for bulk monodomains of rodlike nematic polymers. PMID:16383413

  10. Unusual Photo-Induced Behaviour in a Side Chain Liquid Crystalline Azo-Polyester

    DEFF Research Database (Denmark)

    López, D; Rodríguez, F.J.; Sánchez, C.;

    2006-01-01

    An unusual behaviour has been observed in the photo-indueed response of an azobenzene side chain liquid erystalline polyester (P6d4). Room temperature irradiation with linearly polarised 488 nm light does not induce any birefringence (An) in films of this polymer that have been quenehed from...... the isotropie state. However, using the same irradiation conditions An is indueed in quenehed films that have been kept in darkness for a few minutes. Besides, no photo-induced An is observed in films irradiated with 488 nm light that have been previously irradiated with UV light. In this ease, An can...

  11. Crystalline nucleation in undercooled liquids: A Bayesian data-analysis approach for a nonhomogeneous Poisson process

    Science.gov (United States)

    Filipponi, A.; Di Cicco, A.; Principi, E.

    2012-12-01

    A Bayesian data-analysis approach to data sets of maximum undercooling temperatures recorded in repeated melting-cooling cycles of high-purity samples is proposed. The crystallization phenomenon is described in terms of a nonhomogeneous Poisson process driven by a temperature-dependent sample nucleation rate J(T). The method was extensively tested by computer simulations and applied to real data for undercooled liquid Ge. It proved to be particularly useful in the case of scarce data sets where the usage of binned data would degrade the available experimental information.

  12. Vibrational circular dichroism study of isotropic and liquid crystalline phases formed by guanine quadruplexes

    Czech Academy of Sciences Publication Activity Database

    Andrushchenko, Valery; Tsankov, D.; Krasteva, M.; Wieser, H.; Bouř, Petr

    2012-01-01

    Roč. 19, č. 1 (2012), s. 3-3. ISSN 1210-8529. [10th Discussions in Structural Molecular Biology. 22.03.2012-24.03.2012, Nové Hrady] R&D Projects: GA ČR GAP208/10/0559; GA ČR GAP208/11/0105 Grant ostatní: AV ČR M200550902 Institutional research plan: CEZ:AV0Z40550506 Keywords : G-quadruplexes * DNA * liquid crystals * VCD spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry

  13. Thermal and optical study of semiconducting CNTs-doped nematic liquid crystalline material

    Science.gov (United States)

    Vimal, T.; Singh, D. P.; Gupta, S. K.; Pandey, S.; Agrahari, K.; Manohar, R.

    2016-06-01

    We report the thermal and spectroscopic analysis of the carbon nanotubes (CNTs)-doped nematic liquid crystal (NLC) material. The CNTs have been oriented in the p-ethoxybenzylidene p-butylaniline NLC. The thermal study of the CNTs doped nematic mixtures shows a significant decrease in the isotropic to nematic phase transition temperature. However higher doping concentration of CNTs has led to the further increase in transition temperature. The UV-Visible spectroscopy has been attempted on the CNTs/NLC mixtures at room temperature. The investigated NLC present one absorption band corresponding to π-π* electronic transition. A red shift of λmax with the increasing concentration of CNTs in the mixture has been observed. The band gap of NLC has been found to decrease after the doping of CNTs. The absorbance was measured for the UV light, polarized parallel and perpendicular to the LC director in the planar aligned cell.

  14. Revealing pathologies in the liquid crystalline structures of the brain by polarimetric studies (Presentation Recording)

    Science.gov (United States)

    Bakhshetyan, Karen; Melkonyan, Gurgen G.; Galstian, Tigran V.; Saghatelyan, Armen

    2015-10-01

    Natural or "self" alignment of molecular complexes in living tissue represents many similarities with liquid crystals (LC), which are anisotropic liquids. The orientational characteristics of those complexes may be related to many important functional parameters and their study may reveal important pathologies. The know-how, accumulated thanks to the study of LC materials, may thus be used to this end. One of the traditionally used methods, to characterize those materials, is the polarized light imaging (PLI) that allows for label-free analysis of anisotropic structures in the brain tissue and can be used, for example, for the analysis of myelinated fiber bundles. In the current work, we first attempted to apply the PLI on the mouse histological brain sections to create a map of anisotropic structures using cross-polarizer transmission light. Then we implemented the PLI for comparative study of histological sections of human postmortem brain samples under normal and pathological conditions, such as Parkinson's disease (PD). Imaging the coronal, sagittal and horizontal sections of mouse brain allowed us to create a false color-coded fiber orientation map under polarized light. In human brain datasets for both control and PD groups we measured the pixel intensities in myelin-rich subregions of internal capsule and normalized these to non-myelinated background signal from putamen and caudate nucleus. Quantification of intensities revealed a statistically significant reduction of fiber intensity of PD compared to control subjects (2.801 +/- 0.303 and 3.724 +/- 0.07 respectively; *p < 0.05). Our study confirms the validity of PLI method for visualizing myelinated axonal fibers. This relatively simple technique can become a promising tool for study of neurodegenerative diseases where labeling-free imaging is an important benefit.

  15. Calamitic Smectic A-Polar Smectic APA Transition Observed in Bent Molecules with Large Bent-Angle Central Core of 4,6-Dichlorobenzene and Alkylthio Terminal Tail

    Science.gov (United States)

    Nguyen, Ha; Kang, Sungmin; Tokita, Masatoshi; Watanabe, Junji

    2011-07-01

    New homologs of bent molecules with a large bent-angle central core of 4,6-dichloro benzene and an alkylthio terminal tail have been synthesized. Although the corresponding alkoxy-tail homologs show only the calamitic phases because of its large bent angles around 160°, the new homologs with an alkylthio tail exhibit the antiferroelectric smectic APA (SmAPA) banana phase that is transformed on cooling from the calamitic smectic A (SmA) phase. The biaxial polar packing of bent molecules in the SmAPA phase is considered to arise from the hindered rotation around the molecular long axis due to the expansion of the mesophase temperatures to a lower temperature region. This study indicates that the bent molecules, even with a large bent angle, have the potential to form a switchable banana phase with a remarkable decrease in its phase temperature range to around 60 °C.

  16. Nematic liquid crystalline alignment on graphitic carbon film surfaces and its electrooptical characteristics

    Science.gov (United States)

    Nakagaki, Takamitsu; Yamada, Kenji; Nakamura, Atsushi; Temmyo, Jiro; Kubono, Atsushi

    2015-09-01

    A graphitic carbon (g-C) film directly grown on a synthetic quartz glass substrate was applied to a liquid crystal (LC) device as an alignment layer combined with a transparent electrode for a demonstration of high performance. The as-grown g-C films showed a nanometer-size domain with 91.6% transmittance at 550 nm and with a sheet resistance of 5.9 kΩ/sq. The nanodomain of the g-C film surface was associated with a random orientation of the twisted nematic LC (4-pentyl-4‧-n-cyanobiphenyl, 5CB) molecules in an in-plane randomly parallel alignment that was analyzed by polarized optical microscopy (POM). We also demonstrated an LC display (LCD) in an in-plane random hybrid twisted nematic (IPR-HTN) configuration using the g-C films compared with a previously proposed configuration using a hydroxypropyl cellulose (HPC) sublayer and a TN configuration using a polyimide film with a rubbing treatment. It was found that the combined g-C alignment layer/electrode provides a low turn-on voltage, a fast response, and a wide viewing angle as an orientation sublayer and an electrode.

  17. A charge transfer complex nematic liquid crystalline gel with high electrical conductivity

    International Nuclear Information System (INIS)

    We describe the rheological, dielectric and elastic properties of a nematic liquid crystal gel created using an anthrylidene derivative of arjunolic acid, a chiral triterpenoid, obtained from the extracts of the wood of Terminalia arjuna. In this novel gel, having the electron-donor and acceptor components as minority constituents, the gelation and strengthening of charge-transfer complex (CTC) formation are seen to be occurring concomitantly. In addition to being mechanically strong with a large storage modulus, the gel with the maximized CTC exhibits Frank bend elastic constant values that approach nanonewton levels. The highlight of the study is the observation of 4–5 orders of magnitude increase in electrical conductivity for this gel, a value that is higher than even in the CT complexes of 2-d ordered columnar structures. A further important advantage of the present system over the columnar complex is that the high conductivity is seen for ac probing also, and owing to the nematic nature can be switched between its anisotropic limits. Some of these features are ascribed to a specific molecular packing architecture, which reduces the trapping of the charge carriers.

  18. Calorimetric evidence for the liquid-crystalline state of lipids in a biomembrane.

    Science.gov (United States)

    Steim, J M; Tourtellotte, M E; Reinert, J C; McElhaney, R N; Rader, R L

    1969-05-01

    Both membranes of Mycoplasma laidlawii and water dispersions of protein-free membrane lipids exhibit thermal phase transitions that can be detected by differential scanning calorimetry. The transition temperatures are lowered by increased unsaturation in the fatty acid residues, but in each case they are the same for membranes and lipids. The transitions resemble those observed for synthetic lipids in the lamellar phase in water, which arise from melting of the hydrocarbon chains within the phospholipid bilayers. Such melts are cooperative phenomena and would be greatly perturbed by apolar binding to protein. Thus the identity of membrane and lipid transition temperatures suggests that in the membranes, as in water, the lipids are in the bilayer conformation in which the hydrocarbon chains associate with each other rather than with proteins. Observations of morphological changes indicate that osmotic imbalance occurs when the membrane transition temperature exceeds the growth temperature, and that for transport processes to function properly the hydrocarbon chains must be in a liquid-like state. PMID:5257955

  19. Investigation of the liquid crystalline phase transitions using the new modified Pople-Karasz model

    International Nuclear Information System (INIS)

    Thermodynamics of solid-nematic and nematic-isotropic liquid transitions are studied by using a new modified model that combines the modified theories of Chandrasekhar et al. with those Keskin and Oezgan which are based on the Pople-Karasz theory. The thermodynamic properties of the disordered system are evaluated relative to those of the perfectly ordered one within the lowest approximation of the cluster variation method which is identical to the mean-field approximation. The results are compared with the some available experimental data, the predictions of the original Pople-Karasz (PK) theory and its previous modified theories. For nematic-isotropic and s(nematic) at the transition temperatures, the agreement is very good and much better than the predictions of the PK theory and its previous modified theories. For the solid-nematic transition, all theories give very nearly the same results, but the values are significantly lower than the observed data. Moreover, one of the theoretical phase diagrams is also qualitatively similar to the experimental phase diagram for p-azoxyphenetole (PAA)

  20. A charge transfer complex nematic liquid crystalline gel with high electrical conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Bhargavi, R.; Nair, Geetha G., E-mail: geeraj88@gmail.com, E-mail: skpras@gmail.com; Krishna Prasad, S., E-mail: geeraj88@gmail.com, E-mail: skpras@gmail.com [Centre for Nano and Soft Matter Sciences, Jalahalli, Bangalore 560013 (India); Majumdar, R.; Bag, Braja G. [Department of Chemistry and Chemical Technology, Vidyasagar University, Midnapore (W) 721 102 (India)

    2014-10-21

    We describe the rheological, dielectric and elastic properties of a nematic liquid crystal gel created using an anthrylidene derivative of arjunolic acid, a chiral triterpenoid, obtained from the extracts of the wood of Terminalia arjuna. In this novel gel, having the electron-donor and acceptor components as minority constituents, the gelation and strengthening of charge-transfer complex (CTC) formation are seen to be occurring concomitantly. In addition to being mechanically strong with a large storage modulus, the gel with the maximized CTC exhibits Frank bend elastic constant values that approach nanonewton levels. The highlight of the study is the observation of 4–5 orders of magnitude increase in electrical conductivity for this gel, a value that is higher than even in the CT complexes of 2-d ordered columnar structures. A further important advantage of the present system over the columnar complex is that the high conductivity is seen for ac probing also, and owing to the nematic nature can be switched between its anisotropic limits. Some of these features are ascribed to a specific molecular packing architecture, which reduces the trapping of the charge carriers.

  1. Enhanced skin permeation of 5α-reductase inhibitors entrapped into surface-modified liquid crystalline nanoparticles.

    Science.gov (United States)

    Madheswaran, Thiagarajan; Baskaran, Rengarajan; Sundaramoorthy, Pasupathi; Yoo, Bong Kyu

    2015-04-01

    The objective of this study is to enhance skin permeation of finasteride and dutasteride for the treatment of androgenetic alopecia using surface-modified liquid crystalline nanoparticle (sm-LCN) dispersion. LCN entrapped with the drugs was prepared by using monoolein as a liquid crystal former, and surface modification was performed by treatment of the LCN dispersion with same volume of 1 % v/v acetic acid solution containing chitosan. Physicochemical properties of the LCN's were studied with regard to particle size, polydispersity index, zeta potential, and release of the drugs. Skin permeation of drugs entrapped into the LCN and sm-LCN was investigated with porcine abdominal skin using Franz diffusion cell. Cytotoxicity of the LCN's was also studied using human skin keratinocytes. The particle size and zeta potential of the LCN were 197.9 ± 2.5 nm and -20.2 ± 1.9 mV, respectively, and sm-LCN showed slightly bigger size and positive zeta potential due to the presence of thin coating on the surface of the nanoparticles. Compared to LCN, sm-LCN resulted in significantly enhanced skin permeation of the drugs whereas in vitro release was significantly reduced. Cell viability as a measure of cytotoxicity was above 80 % up to 20 μg/ml concentration of both LCN and sm-LCN. In conclusion, sm-LCN may provide a strategy to maximize therapeutic efficacy minimizing unwanted systemic side effects associated with the use of the drugs for the treatment of androgenetic alopecia. PMID:25085659

  2. Calculation of the Standard Molal Thermodynamic Properties of Crystalline, Liquid, and Gas Organic Molecules at High Temperatures and Pressures

    Science.gov (United States)

    Helgeson, Harold C.; Owens, Christine E.; Knox, Annette M.; Richard, Laurent

    1998-03-01

    Calculation of the thermodynamic properties of organic solids, liquids, and gases at high temperatures and pressures is a requisite for characterizing hydrothermal metastable equilibrium states involving these species and quantifying the chemical affinities of irreversible reactions of organic molecules in natural gas, crude oil, kerogen, and coal with minerals and organic, inorganic, and biomolecular aqueous species in interstitial waters in sedimentary basins. To facilitate calculations of this kind, coefficients for the Parameters From Group Contributions (PFGC) equation of state have been compiled for a variety of groups in organic liquids and gases. In addition, molecular weights, critical temperatures and pressures, densities at 25°C and 1 bar, transition, melting, and boiling temperatures ( Tt,Pr, Tm,Pr, and Tv,Pr, respectively) and standard molal enthalpies of transition (Δ H° t,Pr), melting (Δ H° m,Pr), and vaporization (Δ H° v,Pr) of organic species at 1 bar ( Pr) have been tabulated, together with an internally consistent and comprehensive set of standard molal Gibbs free energies and enthalpies of formation from the elements in their stable state at 298.15 K ( Tr) and Pr (Δ G° f and Δ H° f, respectively). The critical compilation also includes standard molal entropies ( S°) and volumes ( V°) at Tr and Pr, and standard molal heat capacity power function coefficients to compute the standard molal thermodynamic properties of organic solids, liquids, and gases as a function of temperature at 1 bar. These properties and coefficients have been tabulated for more than 500 crystalline solids, liquids, and gases, and those for many more can be computed from the equations of state group additivity algorithms. The crystalline species correspond to normal alkanes (C nH 2( n+1) ) with carbon numbers ( n, which is equal to the number of moles of carbon atoms in one mole of the species) ranging from 5 to 100, and 23 amino acids including glycine (C 2H 5NO

  3. Effects of layer order on the mobility of mesogenic molecules in SmA liquid-crystalline emulsions

    Science.gov (United States)

    Bono, Shinji; Takanishi, Yoichi; Yamamoto, Jun

    2016-03-01

    We fabricate smectic-A liquid-crystalline emulsions (SmA-LCEs) in which monodisperse 8CB-swollen micelles are dispersed in water. Synchrotron X-ray measurements reveal that the correlation length of the layer order in LCEs cannot diverge at the nematic (N)-SmA transition, and the saturated length linearly increases with the increase in the diameter of LC-swollen micelles. Moreover, we investigate the permeation of 7CB N molecules into 8CB SmA-LCEs by measuring the enhancement of the depolarized light scattering intensity due to the shift of the SmA-N phase transition, and confirm that the layer order suppresses the mobility of LC molecules in LCEs similar to the bulk state of SmA LCs. The mobility drastically accelerates near the SmA-N transition temperature due to the continuous extinction of the smectic layer order. The slow permeation process of 7CB is also confirmed via synchrotron X-ray diffraction examining the shrinkage of the smectic layer repeat distance, caused by intercalation of 7CB.

  4. Molecular Packing Determines Charge Separation in a Liquid Crystalline Bisthiophene-Perylene Diimide Donor-Acceptor Material.

    Science.gov (United States)

    Polkehn, Matthias; Tamura, Hiroyuki; Eisenbrandt, Pierre; Haacke, Stefan; Méry, Stéphane; Burghardt, Irene

    2016-04-01

    Combined electronic structure and quantum dynamical calculations are employed to investigate charge separation in a novel class of covalently bound bisthiophene-perylene diimide type donor-acceptor (DA) co-oligomer aggregates. In an earlier spectroscopic study of this DA system in a smectic liquid crystalline (LC) film, efficient and ultrafast (subpicosecond) initial charge separation was found to be followed by rapid recombination. By comparison, the same DA system in solution exhibits ultrafast resonant energy transfer followed by slower (picosecond scale) charge separation. The present first-principles study explains these contrasting observations, highlighting the role of an efficient intermolecular charge-transfer pathway that results from the molecular packing in the LC phase. Despite the efficiency of this primary charge-transfer step, long-range charge separation is impeded by a comparatively high Coulomb barrier in conjunction with small electron- and hole-transfer integrals. Quantum dynamical calculations are carried out for a fragment-based model Hamiltonian, parametrized by ab initio second-order Algebraic Diagrammatic Construction (ADC(2)) and Time-Dependent Density Functional Theory (TDDFT) electronic structure calculations. Simulations of coherent vibronic quantum dynamics for up to 156 electronic states and 48 modes are performed using the Multi-Layer Multi-Configuration Time-Dependent Hartree (ML-MCTDH) method. Excellent agreement with experimentally determined charge separation time scales is obtained, and the spatially coherent nature of the dynamics is analyzed. PMID:26987362

  5. Photovoltaic properties of a ZnO nanorod array affected by ethanol and liquid-crystalline porphyrin

    International Nuclear Information System (INIS)

    A vertically aligned array of ZnO nanorods, fabricated on conductive ITO substrate in aqueous solution, was characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), and UV-visible transmission spectroscopy. Surface photovoltage (SPV) techniques based on a lock-in amplifier and a Kelvin probe were both employed to study the photogenerated charges in the system. The effects of ethanol solvent and a liquid-crystalline porphyrin, [5-(para-dodecyloxy)phenyl-10,15,20-tri-phenyl] porphyrin (DPTPP), on the photovoltage enhancement in the ZnO nanorod array were studied via SPV comparison between different irradiation directions on the system. We demonstrate that the ethanol adsorption could induce the space charge region to expand towards the ZnO/ITO interface. In the absence of ethanol, the ZnO nanorod array with the DPTPP adsorption showed enhanced SPV with reduced attenuation rate of photogenerated charge carriers. We found that the separation of photogenerated charges could be further improved by coating the surface with DPTPP and ethanol together. Furthermore, the SPV spectra patterns of the composite system with opposite incident-light directions reveal that the DPTPP molecules adsorbed just at the surface of ZnO nanorods adopt a more monomeric alignment in contrast to the aggregative state in the DPTPP bulk

  6. Liquid crystalline graphene oxide/PEDOT:PSS self-assembled 3D architecture for binder-free supercapacitor electrodes

    Directory of Open Access Journals (Sweden)

    KonstantinKonstantinov

    2014-08-01

    Full Text Available Binder-free self-assembled 3D architecture electrodes have been fabricated by a novel convienient method. Liquid crystalline graphene oxide (LC GO was used as precursor to interact with poly(3,4-ethylene-dioxythiophene:poly(styrenesulfonate (PEDOT:PSS in dispersion in order to form a conductive polymer entrapped, self-assembled layer-by-layer structure. This advanced network containing PEDOT:PSS enabled us to ascribe the superior electrochemical properties of particular graphene sheets. This layer-by-layer self-assembled 3D architecture of best performing composite (rGO-PEDOT:PSS 25 showed excellent electrochemical performance of 434 F g-1 through chemical treatment. To highlight these advances, we further explored the practicality of the as-prepared electrode by varying the composite material content. An asymmetric supercapacitor device using aqueous electrolyte was also studied of this same composite. The resulting performance from this set up included a specific capacitance of 132 F g-1. Above all, we observed an increase in specific capacitance (19% with increase in cycle life emphasizing the excellent stability of this device.

  7. Biomimetic Nucleation and Morphology Control of CaCO_3 in PAAm Hydrogels Synthesized from Lyotropic Liquid Crystalline Templates

    Institute of Scientific and Technical Information of China (English)

    DU, Zhuwei; LU, Cuixiang; LI, Haoran; LI, Dingjie

    2009-01-01

    Hydrogels have been thought to be the material which can provide appealing replacements of biological organisms. Pores of hydrogeis synthesized from lyotropic liquid crystalline (LLC) templates were smaller in size and more uniform than those of traditional hydrogels. LLC poly-acrylamide (PAAm) hydrogels were used as the growth media of CaCO_3. After copolymerized with acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid (AMPS),LLC hydrogels were modified with COOH and SO_3H, respectively. The effect of functional groups on the biomitactic mineralization of CaCO_3 was studied. Most of crystals from traditional hydrogels are rhombohedral and could not form aggregates. Only a few could aggregate and have a particular morphology with irregular orientation of subcrystal. Compared with crystals separated from traditional hydrogels, crystals growing in the LLC hydrogels were much more regulated and could form aggregates with particular morphology and regular orientation, that is,face (104) of rhombohedral subcrystals parallel to the surface of the macrocrystals. Modification of COOH and SO_3H groups made CaCO_3 subcrystal align more tightly. COOH had minor influences on the crystal orientation and small modification to the aggregate morphology. SO_3H groups could change the crystal orientation and morphology effectively. The aggregates are pseudo-spherical and the face perpendicularity to the face (104) parallels to the surface of the aggregates.

  8. In situ x-ray scattering study of a main-chain thermotropic liquid crystalline polymer under oscillatory shear flow

    Science.gov (United States)

    Vaish, Nitin; Burghardt, Wesley R.; Zhou, Weijun; Kornfield, Julia A.

    2000-03-01

    Liquid crystalline polymers (LCPs) have been the subject of extensive studies because of potential commercial applications and scientific challenges. The excellent mechanical properties of LCPs arise from highly anisotropic molecular structure, which develops as a complex interplay between molecular dynamics and the applied flow field. We study the behavior of model thermotropic main-chain LCP (DHMS-7,9) under oscillatory shear flow using in situ X-ray scattering techniques. Experiments were done in nematic (140^o C) and x-phase (110^o C) to study the effects of frequency (0.5 - 50 rps) and strain amplitude (50 200In nematic phase, strong alignment in the flow direction (‘parallel’) was observed. The steady state was reached quickly either at high strain amplitudes or high frequencies. In x-phase, molecules aligned in flow direction at high strain levels or oscillation frequency, while alignment in vorticity (‘perpendicular’) direction was observed at low strain amplitude or frequency. In addition, we present the flipping of orientation from parallel to perpendicular alignment as a result of step change in temperature from 140^o C to 110^o C and oscillatory motion from a pre-aligned parallel state in x-phase.

  9. Ericksen number and Deborah number cascade predictions of a model for liquid crystalline polymers for simple shear flow

    Science.gov (United States)

    Klein, D. Harley; Leal, L. Gary; García-Cervera, Carlos J.; Ceniceros, Hector D.

    2007-02-01

    We consider the behavior of the Doi-Marrucci-Greco (DMG) model for nematic liquid crystalline polymers in planar shear flow. We found the DMG model to exhibit dynamics in both qualitative and quantitative agreement with experimental observations reported by Larson and Mead [Liq. Cryst. 15, 151 (1993)] for the Ericksen number and Deborah number cascades. For increasing shear rates within the Ericksen number cascade, the DMG model displays three distinct regimes: stable simple shear, stable roll cells, and irregular structure accompanied by disclination formation. In accordance with experimental observations, the model predicts both ±1 and ±1/2 disclinations. Although ±1 defects form via the ridge-splitting mechanism first identified by Feng, Tao, and Leal [J. Fluid Mech. 449, 179 (2001)], a new mechanism is identified for the formation of ±1/2 defects. Within the Deborah number cascade, with increasing Deborah number, the DMG model exhibits a streamwise banded texture, in the absence of disclinations and roll cells, followed by a monodomain wherein the mean orientation lies within the shear plane throughout the domain.

  10. Free volume in imidazolium triflimide ([C3MIM][NTf2]) ionic liquid from positron lifetime: amorphous, crystalline, and liquid states.

    Science.gov (United States)

    Dlubek, G; Yu, Yang; Krause-Rehberg, R; Beichel, W; Bulut, S; Pogodina, N; Krossing, I; Friedrich, Ch

    2010-09-28

    Positron annihilation lifetime spectroscopy (PALS) is used to study the ionic liquid 1-methyl-3-propylimidazolium bis(trifluoromethylsulfonyl)imide [C(3)MIM][NTf(2)] in the temperature range between 150 and 320 K. The positron decay spectra are analyzed using the routine LifeTime-9.0 and the size distribution of local free volumes (subnanometer-size holes) is calculated. This distribution is in good agreement with Fürth's classical hole theory of liquids when taking into account Fürth's hole coalescence hypothesis. During cooling, the liquid sample remains in a supercooled, amorphous state and shows the glass transition in the ortho-positronium (o-Ps) lifetime at 187 K. The mean hole volume varies between 70 Å(3) at 150 K and 250 Å(3) at 265-300 K. From a comparison with the macroscopic volume, the hole density is estimated to be constant at 0.20×10(21) g(-1) corresponding to 0.30 nm(-3) at 265 K. The hole free volume fraction varies from 0.023 at 185 K to 0.073 at T(m)+12 K=265 K and can be estimated to be 0.17 at 430 K. It is shown that the viscosity follows perfectly the Cohen-Turnbull free volume theory when using the free volume determined here. The heating run clearly shows crystallization at 200 K by an abrupt decrease in the mean and standard deviation σ(3) of the o-Ps lifetime distribution and an increase in the o-Ps intensity I(3). The parameters of the second lifetime component and σ(2) behave parallel to the o-Ps parameters, which also shows the positron's (e(+)) response to structural changes. During melting at 253 K, all lifetime parameters recover to the initial values of the liquid. An abrupt decrease in I(3) is attributed to the solvation of e(-) and e(+) particles. Different possible interpretations of the o-Ps lifetime in the crystalline state are briefly discussed. PMID:20886945

  11. Free volume in imidazolium triflimide ([C3MIM][NTf2]) ionic liquid from positron lifetime: Amorphous, crystalline, and liquid states

    International Nuclear Information System (INIS)

    Positron annihilation lifetime spectroscopy (PALS) is used to study the ionic liquid 1-methyl-3-propylimidazolium bis(trifluoromethylsulfonyl)imide [C3MIM][NTf2] in the temperature range between 150 and 320 K. The positron decay spectra are analyzed using the routine LifeTime-9.0 and the size distribution of local free volumes (subnanometer-size holes) is calculated. This distribution is in good agreement with Fuerth's classical hole theory of liquids when taking into account Fuerth's hole coalescence hypothesis. During cooling, the liquid sample remains in a supercooled, amorphous state and shows the glass transition in the ortho-positronium (o-Ps) lifetime at 187 K. The mean hole volume varies between 70 A3 at 150 K and 250 A3 at 265-300 K. From a comparison with the macroscopic volume, the hole density is estimated to be constant at 0.20x1021 g-1 corresponding to 0.30 nm-3 at 265 K. The hole free volume fraction varies from 0.023 at 185 K to 0.073 at Tm+12 K=265 K and can be estimated to be 0.17 at 430 K. It is shown that the viscosity follows perfectly the Cohen-Turnbull free volume theory when using the free volume determined here. The heating run clearly shows crystallization at 200 K by an abrupt decrease in the mean 3> and standard deviation σ3 of the o-Ps lifetime distribution and an increase in the o-Ps intensity I3. The parameters of the second lifetime component 2> and σ2 behave parallel to the o-Ps parameters, which also shows the positron's (e+) response to structural changes. During melting at 253 K, all lifetime parameters recover to the initial values of the liquid. An abrupt decrease in I3 is attributed to the solvation of e- and e+ particles. Different possible interpretations of the o-Ps lifetime in the crystalline state are briefly discussed.

  12. Liquid Crystalline Nanoparticles as an Ophthalmic Delivery System for Tetrandrine: Development, Characterization, and In Vitro and In Vivo Evaluation

    Science.gov (United States)

    Liu, Rui; Wang, Shuangshuang; Fang, Shiming; Wang, Jialu; Chen, Jingjing; Huang, Xingguo; He, Xin; Liu, Changxiao

    2016-05-01

    The purpose of this study was to develop novel liquid crystalline nanoparticles (LCNPs) that display improved pre-ocular residence time and ocular bioavailability and that can be used as an ophthalmic delivery system for tetrandrine (TET). The delivery system consisted of three primary components, including glyceryl monoolein, poloxamer 407, and water, and two secondary components, including Gelucire 44/14 and amphipathic octadecyl-quaternized carboxymethyl chitosan. The amount of TET, the amount of glyceryl monoolein, and the ratio of poloxamer 407 to glyceryl monoolein were selected as the factors that were used to optimize the dependent variables, which included encapsulation efficiency and drug loading. A three-factor, five-level central composite design was constructed to optimize the formulation. TET-loaded LCNPs (TET-LCNPs) were characterized to determine their particle size, zeta potential, entrapment efficiency, drug loading capacity, particle morphology, inner crystalline structure, and in vitro drug release profile. Corneal permeation in excised rabbit corneas was evaluated. Pre-ocular retention was determined using a noninvasive fluorescence imaging system. Finally, pharmacokinetic study in the aqueous humor was performed by microdialysis technique. The optimal formulation had a mean particle size of 170.0 ± 13.34 nm, a homogeneous distribution with polydispersity index of 0.166 ± 0.02, a positive surface charge with a zeta potential of 29.3 ± 1.25 mV, a high entrapment efficiency of 95.46 ± 4.13 %, and a drug loading rate of 1.63 ± 0.07 %. Transmission electron microscopy showed spherical particles that had smooth surfaces. Small-angle X-ray scattering profiles revealed an inverted hexagonal phase. The in vitro release assays showed a sustained drug release profile. A corneal permeation study showed that the apparent permeability coefficient of the optimal formulation was 2.03-fold higher than that of the TET solution. Pre-ocular retention

  13. Liquid Crystalline Nanoparticles as an Ophthalmic Delivery System for Tetrandrine: Development, Characterization, and In Vitro and In Vivo Evaluation

    Science.gov (United States)

    Liu, Rui; Wang, Shuangshuang; Fang, Shiming; Wang, Jialu; Chen, Jingjing; Huang, Xingguo; He, Xin; Liu, Changxiao

    2016-05-01

    The purpose of this study was to develop novel liquid crystalline nanoparticles (LCNPs) that display improved pre-ocular residence time and ocular bioavailability and that can be used as an ophthalmic delivery system for tetrandrine (TET). The delivery system consisted of three primary components, including glyceryl monoolein, poloxamer 407, and water, and two secondary components, including Gelucire 44/14 and amphipathic octadecyl-quaternized carboxymethyl chitosan. The amount of TET, the amount of glyceryl monoolein, and the ratio of poloxamer 407 to glyceryl monoolein were selected as the factors that were used to optimize the dependent variables, which included encapsulation efficiency and drug loading. A three-factor, five-level central composite design was constructed to optimize the formulation. TET-loaded LCNPs (TET-LCNPs) were characterized to determine their particle size, zeta potential, entrapment efficiency, drug loading capacity, particle morphology, inner crystalline structure, and in vitro drug release profile. Corneal permeation in excised rabbit corneas was evaluated. Pre-ocular retention was determined using a noninvasive fluorescence imaging system. Finally, pharmacokinetic study in the aqueous humor was performed by microdialysis technique. The optimal formulation had a mean particle size of 170.0 ± 13.34 nm, a homogeneous distribution with polydispersity index of 0.166 ± 0.02, a positive surface charge with a zeta potential of 29.3 ± 1.25 mV, a high entrapment efficiency of 95.46 ± 4.13 %, and a drug loading rate of 1.63 ± 0.07 %. Transmission electron microscopy showed spherical particles that had smooth surfaces. Small-angle X-ray scattering profiles revealed an inverted hexagonal phase. The in vitro release assays showed a sustained drug release profile. A corneal permeation study showed that the apparent permeability coefficient of the optimal formulation was 2.03-fold higher than that of the TET solution. Pre-ocular retention

  14. Liquid Crystalline Nanoparticles as an Ophthalmic Delivery System for Tetrandrine: Development, Characterization, and In Vitro and In Vivo Evaluation.

    Science.gov (United States)

    Liu, Rui; Wang, Shuangshuang; Fang, Shiming; Wang, Jialu; Chen, Jingjing; Huang, Xingguo; He, Xin; Liu, Changxiao

    2016-12-01

    The purpose of this study was to develop novel liquid crystalline nanoparticles (LCNPs) that display improved pre-ocular residence time and ocular bioavailability and that can be used as an ophthalmic delivery system for tetrandrine (TET). The delivery system consisted of three primary components, including glyceryl monoolein, poloxamer 407, and water, and two secondary components, including Gelucire 44/14 and amphipathic octadecyl-quaternized carboxymethyl chitosan. The amount of TET, the amount of glyceryl monoolein, and the ratio of poloxamer 407 to glyceryl monoolein were selected as the factors that were used to optimize the dependent variables, which included encapsulation efficiency and drug loading. A three-factor, five-level central composite design was constructed to optimize the formulation. TET-loaded LCNPs (TET-LCNPs) were characterized to determine their particle size, zeta potential, entrapment efficiency, drug loading capacity, particle morphology, inner crystalline structure, and in vitro drug release profile. Corneal permeation in excised rabbit corneas was evaluated. Pre-ocular retention was determined using a noninvasive fluorescence imaging system. Finally, pharmacokinetic study in the aqueous humor was performed by microdialysis technique. The optimal formulation had a mean particle size of 170.0 ± 13.34 nm, a homogeneous distribution with polydispersity index of 0.166 ± 0.02, a positive surface charge with a zeta potential of 29.3 ± 1.25 mV, a high entrapment efficiency of 95.46 ± 4.13 %, and a drug loading rate of 1.63 ± 0.07 %. Transmission electron microscopy showed spherical particles that had smooth surfaces. Small-angle X-ray scattering profiles revealed an inverted hexagonal phase. The in vitro release assays showed a sustained drug release profile. A corneal permeation study showed that the apparent permeability coefficient of the optimal formulation was 2.03-fold higher than that of the TET solution. Pre

  15. Modulating alignment of membrane proteins in liquid-crystalline and oriented gel media by changing the size and charge of phospholipid bicelles

    International Nuclear Information System (INIS)

    We demonstrate that alignment of a structured peptide or small protein solubilized in mixed phospholipid:detergent micelles or bicelles, when embedded in a compressed gel or liquid crystalline medium, can be altered by either changing the phospholipid aggregate shape, charge, or both together. For the hemagglutinin fusion peptide solubilized in bicelles, we show that bicelle shape and charge do not change its helical hairpin structure but impact its alignment relative to the alignment medium, both in charged compressed acrylamide gel and in liquid crystalline d(GpG). The method can be used to generate sets of residual dipolar couplings that correspond to orthogonal alignment tensors, and holds promise for high-resolution structural refinement and dynamic mapping of membrane proteins.

  16. PEGylation of Phytantriol-Based Lyotropic Liquid Crystalline Particles-The Effect of Lipid Composition, PEG Chain Length, and Temperature on the Internal Nanostructure

    DEFF Research Database (Denmark)

    Nilsson, Christa; Ostergaard, Jesper; Larsen, Susan Weng;

    2014-01-01

    Poly(ethylene glycol)-grafted 1,2-distearoyl-sn-glycero-3-phosphoethanolamines (DSPE-mPEGs) are a family of amphiphilic lipopolymers attractive in formulating injectable long-circulating nanoparticulate drug formulations. In addition to long circulating liposomes, there is an interest in developing...... injectable long-circulating drug nanocarriers based on cubosomes and hexosomes by shielding and coating the dispersed particles enveloping well-defined internal nonlamellar liquid crystalline nanostructures with hydrophilic PEG segments. The present study attempts to shed light on the possible PEGylation of...... these lipidic nonlamellar liquid crystalline particles by using DSPE-mPEGs with three different block lengths of the hydrophilic PEG segment. The effects of lipid composition, PEG chain length, and temperature on the morphology and internal nanostructure of these self-assembled lipidic aqueous...

  17. Modulating alignment of membrane proteins in liquid-crystalline and oriented gel media by changing the size and charge of phospholipid bicelles

    Energy Technology Data Exchange (ETDEWEB)

    Lorieau, Justin L.; Maltsev, Alexander S.; Louis, John M.; Bax, Ad, E-mail: bax@nih.gov [National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health, Laboratory of Chemical Physics (United States)

    2013-04-15

    We demonstrate that alignment of a structured peptide or small protein solubilized in mixed phospholipid:detergent micelles or bicelles, when embedded in a compressed gel or liquid crystalline medium, can be altered by either changing the phospholipid aggregate shape, charge, or both together. For the hemagglutinin fusion peptide solubilized in bicelles, we show that bicelle shape and charge do not change its helical hairpin structure but impact its alignment relative to the alignment medium, both in charged compressed acrylamide gel and in liquid crystalline d(GpG). The method can be used to generate sets of residual dipolar couplings that correspond to orthogonal alignment tensors, and holds promise for high-resolution structural refinement and dynamic mapping of membrane proteins.

  18. Improved Cross Validation of a Static Ubiquitin Structure Derived from High Precision Residual Dipolar Couplings Measured in a Drug-Based Liquid Crystalline Phase

    OpenAIRE

    Maltsev, Alexander S.; Grishaev, Alexander; Roche, Julien; Zasloff, Michael; Bax, Ad

    2014-01-01

    The antibiotic squalamine forms a lyotropic liquid crystal at very low concentrations in water (0.3-3.5% w/v), which remains stable over a wide range of temperature (1-40 °C) and pH (4-8). Squalamine is positively charged, and comparison of the alignment of ubiquitin relative to 36 previously reported alignment conditions shows that it differs substantially from most of these, but is closest to liquid crystalline cetyl pyridinium bromide. High precision residual dipolar couplings (RDCs) measu...

  19. The importance of orientation in proton transport of a polymer film based on an oriented self-organized columnar liquid-crystalline polyether

    International Nuclear Information System (INIS)

    We prepared membranes based on a liquid-crystalline side-chain polyether obtained by chemical modification of commercial poly(epichlorohydrin) (PECH) with dendrons. This polymer exhibited a columnar structure, which could form an ion channel in the inner part. The columns were successfully oriented by taking advantage of surface interactions between the polymer and hydrophilic substrates, as confirmed by X-ray diffraction analysis (XRD), environmental scanning electron microscopy (ESEM) and optical microscopy between crossed polars (POM). Column orientation was found to be crucial for effective transport: the oriented membranes exhibited proton transport comparable to that of Nafion® N117 and no water uptake. An increase in sodium ion concentration in the feed phase suggested a proton/cation antiport. On the contrary, no proton transport was detected on unoriented membranes based on the same liquid-crystalline side-chain polyether or on unmodified PECH. - Highlights: ► We prepared oriented membranes based on a liquid crystalline columnar polyether. ► In this structure, the inner polyether chain could work as an ion channel. ► We obtained membranes by casting a chloroform solution in the presence of water. ► Membranes showed good proton permeability due to the presence of oriented channels.

  20. The importance of orientation in proton transport of a polymer film based on an oriented self-organized columnar liquid-crystalline polyether

    Energy Technology Data Exchange (ETDEWEB)

    Tylkowski, Bartosz; Castelao, Nuria [Departament d' Enginyeria Quimica, Universitat Rovira i Virgili, Av. Paiesos Catalans, 26, E-43007, Tarragona (Spain); Giamberini, Marta, E-mail: marta.giamberini@urv.net [Departament d' Enginyeria Quimica, Universitat Rovira i Virgili, Av. Paiesos Catalans, 26, E-43007, Tarragona (Spain); Garcia-Valls, Ricard [Departament d' Enginyeria Quimica, Universitat Rovira i Virgili, Av. Paiesos Catalans, 26, E-43007, Tarragona (Spain); Reina, Jose Antonio [Departament de Quimica Analitica i Quimica Organica, Universitat Rovira i Virgili, Carrer Marcel.li Domingo s/n, E-43007, Tarragona (Spain); Gumi, Tania [Departament d' Enginyeria Quimica, Universitat Rovira i Virgili, Av. Paiesos Catalans, 26, E-43007, Tarragona (Spain)

    2012-02-01

    We prepared membranes based on a liquid-crystalline side-chain polyether obtained by chemical modification of commercial poly(epichlorohydrin) (PECH) with dendrons. This polymer exhibited a columnar structure, which could form an ion channel in the inner part. The columns were successfully oriented by taking advantage of surface interactions between the polymer and hydrophilic substrates, as confirmed by X-ray diffraction analysis (XRD), environmental scanning electron microscopy (ESEM) and optical microscopy between crossed polars (POM). Column orientation was found to be crucial for effective transport: the oriented membranes exhibited proton transport comparable to that of Nafion Registered-Sign N117 and no water uptake. An increase in sodium ion concentration in the feed phase suggested a proton/cation antiport. On the contrary, no proton transport was detected on unoriented membranes based on the same liquid-crystalline side-chain polyether or on unmodified PECH. - Highlights: Black-Right-Pointing-Pointer We prepared oriented membranes based on a liquid crystalline columnar polyether. Black-Right-Pointing-Pointer In this structure, the inner polyether chain could work as an ion channel. Black-Right-Pointing-Pointer We obtained membranes by casting a chloroform solution in the presence of water. Black-Right-Pointing-Pointer Membranes showed good proton permeability due to the presence of oriented channels.

  1. Resveratrol-Loaded Liquid-Crystalline System Inhibits UVB-Induced Skin Inflammation and Oxidative Stress in Mice.

    Science.gov (United States)

    Fujimura, Andressa T; Martinez, Renata M; Pinho-Ribeiro, Felipe A; Lopes Dias da Silva, Amélia M; Baracat, Marcela M; Georgetti, Sandra R; Verri, Waldiceu A; Chorilli, Marlus; Casagrande, Rubia

    2016-05-27

    Evidence shows beneficial effects of resveratrol (RES) on human health. However, its poor aqueous solubility limits therapeutic effectiveness. Thus, the use of nanostructured delivery systems for RES, such as a liquid-crystalline system (LCS), could be viable. The purpose of this study was to develop, characterize, and determine the in vivo effectiveness of a RES-loaded LCS. We studied an LCS containing silicon glycol copolymer, polyether functional siloxane, and the polymeric dispersion carbomer homopolymer type B (C974) in the ratio 20:55:25 with and without RES. Results obtained using polarized light microscopy, small-angle X-ray scattering, and rheology analysis showed that the RES-loaded LCS system presents a lamellar structure and behaves as a non-Newtonian fluid presenting pseudoplastic (the apparent viscosity decreases as the stress increases) and thixotropic (the apparent viscosity decreases with the duration of stress) behaviors. Cytotoxicity studies showed that the formulation components are noncytotoxic. Topical application of a RES-loaded LCS protected hairless mice from UVB-irradiation-induced skin damage by inhibiting edema, neutrophil recruitment, lipid hydroperoxide and superoxide anion production, gp91phox mRNA expression, and oxidative stress. The RES-loaded LCS maintained 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and ferric reducing abilities, catalase activity, reduced glutathione levels, and mRNA expression of glutathione peroxidase 1 and glutathione reductase. The RES-loaded LCS also up-regulated matrix metalloproteinase-9 activity, IL-10 production, and mRNA expression of transcription factor Nrf2 and heme oxygenase-1. Therefore, a RES-loaded LCS is a promising new therapeutic approach to mitigate skin photodamage. PMID:27191910

  2. Deuteron nuclear-resonance studies on liquid-crystalline polymers. Collective motions, director dynamics, and viscoelastic properties

    International Nuclear Information System (INIS)

    Nuclear magnetic resonance (NMR) spectroscopy was used to investigate the molecular dynamics of specifically deuterated main-chain side-chain liquid crystalline polymer systems. Special emphasis was put on the dynamics in the nematic phase. Analysis of Carr-Purcell-Meiboom-Gill (CPMG) experiments showed, that the transverse deuterium-NMR relaxation of the polymers in this phase is dominated by slow collective motions. The dispersion law observed for the CPMG relaxation times is characteristic for nematic director fluctuations. To characterize the dynamics of the nematic director in a strong magnetic field, the time development of the deuterium-NMR spectra of the polymer systems after a step rotation of the probe is monitored. Analysis of the line shapes of the time dependent deuterium-NMR spectra shows that the reorientation after a step rotation by 90 occurs through a spatially periodic transient perturbation of the director field. This analysis yields information about the time development of the director orientation which can be analyzed based on Leslie-Ericksen theory to obtain detailed information about the viscoelastic behaviour of the investigated polymers: four out of five independent viscosities of the nematic phase, as well as the ratio of splay and bend elastic constants can be determined. If one inserts these results into the analysis of the CPMG experiments, one obtains - with the help of a newly developed slow motional model absolute values for the anisotropic elastic constants. Thus, one can determine for the first time an almost complete set of viscoelastic parameters for thermotropic main chain polymers. These results are of great importance for technological application of the polymers. In addition they can be used to confirm postulated scaling laws for the viscoelastic parameters of these systems. It can be shown that the particularly large splay elasticity corresponds well with the theoretical predictions by de Gennes. (Orig.)

  3. Self-assembled nano-architecture liquid crystalline particles as a promising carrier for progesterone transdermal delivery.

    Science.gov (United States)

    Elgindy, Nazik A; Mehanna, Mohammed M; Mohyeldin, Salma M

    2016-03-30

    The study aims to elaborate novel self-assembled liquid crystalline nanoparticles (LCNPs) for management of hormonal disturbances following non-invasive progesterone transdermal delivery. Fabrication and optimization of progesteroneloaded LCNPs for transdermal delivery were assessed via a quality by design approach based on 2(3) full factorial design. The design includes the functional relationships between independent processing variables and dependent responses of particle size, polydispersity index, zeta potential, cumulative drug released after 24h and ex-vivo transdermal steady flux. The developed nanocarrier was subjected to TEM (transmission electron microscope) for morphological elucidation and stability study within a period of three months at different storage temperatures. The cubic phase of LCNPs was successfully prepared using glyceryl monooleate (GMO) via the emulsification technique. Based on the factorial design, the independent operating variables significantly affected the five dependent responses. The cubosomes hydrodynamic diameters were in the nanometric range (101-386 nm) with narrow particle size distribution, high negative zeta potential ≥-30 mV and entrapment efficiency ≥94%. The LCNPs succeeded in sustaining progesterone release for almost 24h, following a non-fickian transport of drug diffusion mechanism. Ex-vivo study revealed a significant enhancement up to 6 folds in the transdermal permeation of progesterone-loaded LCNPs compared to its aqueous suspension. The optimized LCNPs exhibited a high physical stability while retaining the cubic structure for at least three months. Quality by design approach successfully accomplished a predictable mathematical model permitting the development of novel LCNPs for transdermal delivery of progesterone with the benefit of reducing its oral route side effects. PMID:26828671

  4. Synthesis of Programmable Main-chain Liquid-crystalline Elastomers Using a Two-stage Thiol-acrylate Reaction.

    Science.gov (United States)

    Saed, Mohand O; Torbati, Amir H; Nair, Devatha P; Yakacki, Christopher M

    2016-01-01

    This study presents a novel two-stage thiol-acrylate Michael addition-photopolymerization (TAMAP) reaction to prepare main-chain liquid-crystalline elastomers (LCEs) with facile control over network structure and programming of an aligned monodomain. Tailored LCE networks were synthesized using routine mixing of commercially available starting materials and pouring monomer solutions into molds to cure. An initial polydomain LCE network is formed via a self-limiting thiol-acrylate Michael-addition reaction. Strain-to-failure and glass transition behavior were investigated as a function of crosslinking monomer, pentaerythritol tetrakis(3-mercaptopropionate) (PETMP). An example non-stoichiometric system of 15 mol% PETMP thiol groups and an excess of 15 mol% acrylate groups was used to demonstrate the robust nature of the material. The LCE formed an aligned and transparent monodomain when stretched, with a maximum failure strain over 600%. Stretched LCE samples were able to demonstrate both stress-driven thermal actuation when held under a constant bias stress or the shape-memory effect when stretched and unloaded. A permanently programmed monodomain was achieved via a second-stage photopolymerization reaction of the excess acrylate groups when the sample was in the stretched state. LCE samples were photo-cured and programmed at 100%, 200%, 300%, and 400% strain, with all samples demonstrating over 90% shape fixity when unloaded. The magnitude of total stress-free actuation increased from 35% to 115% with increased programming strain. Overall, the two-stage TAMAP methodology is presented as a powerful tool to prepare main-chain LCE systems and explore structure-property-performance relationships in these fascinating stimuli-sensitive materials. PMID:26862925

  5. Mesomorphism and electrochemistry of thienoviologen liquid crystals.

    Science.gov (United States)

    Cospito, S; Beneduci, A; Veltri, L; Salamonczyk, M; Chidichimo, G

    2015-07-21

    The thienoviologen series 4,4'-(2,2'-bithiophene-5,5'-diyl)bis(1-alkylpridinium)X2, with = counterion is a new class of electron acceptor materials which show very interesting electrochromic and electrofluorescence properties. Depending on the length, m, of the promesogenic alkyl chains, and on the counterion, thienoviologens might become liquid crystals. Here, we present the mesomorphic behaviour, and the electrochemical and spectroelectrochemical properties in solution of new thienoviologens of the series and (I = iodide; NTf2(-) = bis(tri-fuoromethylsulfonyl)imide) with m = 8, 12. Interestingly, we found that only the compounds are liquid crystals, exhibiting a calamitic behaviour in contrast to the homologous compounds of the series with m = 9-11 and X = NTf2(-), which showed columnar rectangular mesophases. The electrochemical study here reported allowed us to explain for the first time the anomalous behaviour of these thienoviologens already observed in cyclic voltammetry, where two apparently irreversible redox processes occur. This can be explained by a comproportionation reaction in which the neutral species rapidly reduces the dication to the radical-cation, due to its strong reducing power. Electrochemical reduction of the thienoviologens causes electrochromism since a new absorption band, occurring at 660 nm in the electronic spectra, appears with the negative potential bias applied. With a LUMO level of 3.64 eV, similar to those of the C60 and of other n-type materials, these compounds can find applications in several electronics devices, where their liquid crystalline properties can be used to control film morphology and geometry, provided they have good electron mobility. PMID:26082287

  6. Temperature effects on capillary instabilities in a thin nematic liquid crystalline fiber embedded in a viscous matrix

    Science.gov (United States)

    Cheong, A.-G.; Rey, A. D.

    2002-10-01

    Linear stability analysis of capillary instabilities in a thin nematic liquid crystalline cylindrical fiber embedded in an immiscible viscous matrix is performed by formulating and solving the governing nemato-capillary equations, that include the effect of temperature on the nematic ordering as well as the effect of the nematic orientation. A representative axial nematic orientation texture with the planar easy axis at the fiber surface is studied. The surface disturbance is expressed in normal modes, which include the azimuthal wave number m to take into account non-axisymmetric modes. Capillary instabilities in nematic fibers reflect the anisotropic nature of liquid crystals, such as the ordering and orientation contributions to the surface elasticity and surface normal and bending stresses. Surface gradients of normal and bending stresses provide additional anisotropic contributions to the capillary pressure that may renormalize the classical displacement and curvature forces that exist in any fluid fiber. The exact nature (stabilizing and destabilizing) and magnitude of the renormalization of the displacement and curvature forces depend on the nematic ordering and orientation, i.e. the anisotropic contribution to the surface energy, and accordingly capillary instabilities may be axisymmetric or non-axisymmetric. In addition, when the interface curvature effects are accounted for as contributions of the work of interfacial bending and torsion to the total energy of the system, the higher-order bending moment contribution to the surface stress tensor is critical in stabilizing the fiber instabilities. For the planar easy axis, the nematic ordering contribution to the surface energy, which renormalizes the effect of the fiber shape, plays a crucial role to determine the instability mechanisms. Moreover, the unstable modes, which are most likely observed, can be driven by the dependence of surface energy on the surface area. Low-ordering fibers display the

  7. Effect of trans-cis photoisomerization on phase equilibria and phase transition of liquid-crystalline azobenzene chromophore and its blends with reactive mesogenic diacrylate.

    Science.gov (United States)

    Kim, Namil; Li, Quan; Kyu, Thein

    2011-03-01

    Photoisomerization-induced phase transition of neat liquid-crystalline azobenzene chromophore (LCAC) and its effect on phase diagrams of its mixtures with reactive mesogenic diacrylate monomer (RM257) have been investigated experimentally and theoretically. Upon irradiation with ultraviolet light, the nematic phase of LCAC transformed to isotropic, while the crystal phase showed corrugated textures on the surface (i.e., ripples). The phase-transition temperatures and corresponding morphologies of the blends have been investigated by means of differential scanning calorimetry and optical microscopy. A theoretical phase diagram of a binary nematic and crystalline system was constructed by self-consistently solving the combined free energies of Flory-Huggins, Maier-Saupe, and phase-field theory. The calculation revealed various coexistence regions such as nematic + liquid (N₁ + L₂), crystal + liquid (Cr₁ + L₂), crystal + nematic (Cr₁ + N₂), and crystal + crystal (Cr₁ + Cr₂) over a broad range of compositions including the single-phase nematic (N₁, N₂) of the corresponding constituents. The calculated liquidus lines were in good accord with the depressed mesophase-isotropic transition points. The present paper demonstrates the effect of trans-cis photoisomerization on the mesophase transitions of neat LCAC and the phase diagram of LCAC-RM257 as well as on the ripple formation (i.e., periodic undulation) on the azobenzene crystals. PMID:21517513

  8. Influence of hydrogen bonding on the generation and stabilization of liquid crystalline polyesters, poly(esteramide)s and polyacrylates

    Indian Academy of Sciences (India)

    C K S Pillai; K Y Sandhya; J D Sudha; M Saminathan

    2003-08-01

    Induction and stabilization of liquid crystallinity through hydrogen bonding (HB) are now well-established. Interesting observations made on the influence of HB on LC behaviour of amido diol-based poly(esteramide)s, poly(esteramide)s containing nitro groups and azobenzene mesogen-based polyacrylates will be discussed. The use of amido diol as an important precursor for the synthesis of novel PEAs containing inbuilt di-amide linkage enabled generation of extensive hydrogen bondings between the amide–amide and amide–ester groups which stabilized the mesophase structures of the PEAs. The contributions of hydrogen bonding to the generation and stabilization of mesophase structures were plainly evident from the observation of liquid crystallinity even in PEAs prepared from fully aliphatic amido diols. Replacement of terephthaloyl units by isophthaloyl moiety totally vanquished liquid crystalline phases while biphenylene and naphthalene units did only reduce the transition temperatures as expected. The occurrence of the smectic phases in some of the polymers indicated possibly self-assembly through the formation of hetero intermolecular hydrogen bonded networks. A smectic polymorphism and in addition, a smectic-to-nematic transition, were observed in the monomers and polymers based on 1,4-phenylene[bis-(3-nitroanthranilidic acid)] containing nitro groups. A smectic polymorphism was also observed as a combined effect of hydrogen bonded carboxyl groups and laterally substituted alkyl side chains in the case of azobenzene mesogen containing side chain polyacrylates. It was further shown that the presence of the mesophase enhances the non-linear optical (NLO) response of these polymers.

  9. Photoorientation of a liquid-crystalline polyester with azobenzene side groups: Effects of irradiation with linearly polarized red light after photochemical pretreatment

    DEFF Research Database (Denmark)

    Zebger, Ingo; Rutloh, Michael; Hoffmann, Uwe;

    2003-01-01

    In contrast to the conventional photoorientation process with blue light, an orientation of 4-cyano-4'-alkoxyazobenzene side groups parallel to the electric field vector of the incident light is generated upon irradiating films of a liquid-crystalline side-chain polymer with linearly polarized red...... light. The polyester is characterized by smectic and nematic phases g24SX26SA34N46i and a strong tendency to form J-aggregates. The process requires a photochemical pretreatment by irradiation with UV light or an exposure to visible light of high power density to produce a certain concentration of the Z...

  10. Lipid-based liquid crystalline nanoparticles as oral drug delivery vehicles for poorly water-soluble drugs: cellular interaction and in vivo absorption

    Directory of Open Access Journals (Sweden)

    Zeng N

    2012-07-01

    Full Text Available Ni Zeng,1,3,* Xiaoling Gao,2,* Quanyin Hu,1 Qingxiang Song,2 Huimin Xia,1 Zhongyang Liu,1 Guangzhi Gu,1 Mengyin Jiang,1,4 Zhiqing Pang,1 Hongzhuan Chen,2 Jun Chen,1 Liang Fang3 1Key Laboratory of Smart Drug Delivery, Ministry of Education and PLA, School of Pharmacy, Fudan University, Shanghai, 2Department of Pharmacology, Institute of Medical Sciences, Shanghai Jiaotong University School of Medicine, Shanghai, 3Department of Pharmaceutical Science, School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, Liaoning, 4School of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan, Shandong People's Republic of China, *These authors contributed equally to this workBackground: Lipid-based liquid crystalline nanoparticles (LCNPs have attracted growing interest as novel drug-delivery systems for improving the bioavailability of both hydrophilic and hydrophobic drugs. However, their cellular interaction and in vivo behavior have not been fully developed and characterized.Methods: In this study, self-assembled LCNPs prepared from soy phosphatidylcholine and glycerol dioleate were developed as a platform for oral delivery of paclitaxel. The particle size of empty LCNPs and paclitaxel-loaded LCNPs was around 80 nm. The phase behavior of the liquid crystalline matrix was characterized using crossed polarized light microscopy and small-angle X-ray scattering, and showed both reversed cubic and hexagonal phase in the liquid crystalline matrix. Transmission electron microscopy and cryofield emission scanning electron microscopy analysis revealed an inner winding water channel in LCNPs and a "ball-like"/"hexagonal" morphology.Results: Cellular uptake of LCNPs in Caco-2 cells was found to be concentration-dependent and time-dependent, with involvement of both clathrin and caveolae/lipid raft-mediated endocytosis. Under confocal laser scanning microscopy, soy phosphatidylcholine was observed to segregate from the internalized LCNPs and

  11. RNAi mediated IL-6 in vitro knockdown in psoriasis skin model with topical siRNA delivery system based on liquid crystalline phase.

    Science.gov (United States)

    Depieri, Lívia Vieira; Borgheti-Cardoso, Lívia Neves; Campos, Patrícia Mazureki; Otaguiri, Katia Kaori; Vicentini, Fabiana Testa Moura de Carvalho; Lopes, Luciana Biagini; Fonseca, Maria José Vieira; Bentley, M Vitória Lopes Badra

    2016-08-01

    Gene therapy by RNA interference (RNAi) is a post-transcriptional silencing process that can suppress the expression of a particular gene and it is a promising therapeutic approach for the treatment of many severe diseases, including cutaneous disorders. However, difficulties related to administration and body distribution limit the clinical use of small interfering RNA (siRNA) molecules. In this study, we proposed to use nanocarriers to enable siRNA application in the topical treatment of skin disorders. A siRNA nanodispersion based on liquid crystalline phase and composed of monoolein (MO), oleic acid (OA) and polyethylenimine (PEI) was developed and its physicochemical properties, efficiency of complexation and carrier/siRNA stability were assessed. Subsequently, cell viability, cellular uptake, in vitro skin irritation test using reconstructed human epidermis (RHE) and in vitro IL-6 knockdown in psoriasis skin model were evaluated. The results showed that the liquid crystalline nanodispersion is a promising topical delivery system for administration of siRNA, being able to overcome the limitations of the route of administration, as well those resulting from the characteristics of siRNA molecules. The formulation was effective at complexing the siRNA, presented high rate of cell uptake (∼90%), increased the skin penetration of siRNA in vitro, and did not cause skin irritation compared with Triton-X (a moderate irritant), resulting in a 4-fold higher viability of reconstructed human epidermis and a 15.6-fold lower release of IL-1α. A single treatment with the liquid crystalline nanodispersion carrying IL-6 siRNA for 6h was able to reduce the extracellular IL-6 levels by 3.3-fold compared with control treatment in psoriasis skin model. Therefore, liquid crystalline nanodispersion is a suitable nanocarrier for siRNA with therapeutic potential to suppress skin disease-specific genes. This study also highlights the applicability of reconstructed skin models in

  12. Correlation between hydrophobic and molecular shape descriptors and retention data of polycyclic aromatic hydrocarbons in reversed-phase chromatography on non-liquid-crystalline, nematic, and smectic stationary phases

    Energy Technology Data Exchange (ETDEWEB)

    Gritti, F. [E.N.S.C.P.B. Universite Bordeaux, Pessac (France); C.R.P.P., CNRS, Universite Bordeaux, Pessac (France); Sourigues, S.; Felix, G. [E.N.S.C.P.B. Universite Bordeaux, Pessac (France); Achard, M.F.; Hardouin, F. [C.R.P.P., CNRS, Universite Bordeaux, Pessac (France)

    2002-07-01

    The local anisotropic ordering of side-chain liquid-crystalline polymer (SCLCP) stationary phases has been revealed statistically. For this purpose the RP HPLC separation of polycyclic aromatic hydrocarbons (PAH) on silica coated with three classes (non-liquid-crystalline, nematic, and smectic) of side-chain polymer (SCP) has been compared. The logarithm of the capacity factor (log k) was correlated with three PAH descriptors - the connectivity index ({chi}) or the hydrophobic fragmental constant (log P), the length-to-breadth ratio (L/B), and a non-planarity term (N{sub p}). Statistical results revealed good correlation between the model and experimental data, enabling the different stationary phases to be compared. Recognition of solute size seems similar for each class of polymer but solute non-planarity recognition grows continuously as ordering of the liquid-crystal polymer increases. Recognition of solute lengthening is non-existent for non-liquid-crystalline polymers and suddenly appears with liquid crystalline polymers. Shape recognition is better for smectic than for nematic SCP. The predictive ability of this model was tested on highly condensed aromatic compounds. The connectivity index {chi} did not seem appropriate for such systems. Its replacement by Rekker's hydrophobic fragmental constant, log P, was necessary for fitting the retention of these solutes on liquid-crystalline stationary phases. (orig.)

  13. In-situ ultrasonic compatibilization of binary blends of flexible chain polyesters and aromatic liquid crystalline polymers

    Science.gov (United States)

    Gunes, Kaan

    The objective of this research was to improve the properties of immiscible polymer blends by developing a new ultrasonic extrusion process. The ability of ultrasonic treatment to induce recombination reactions in polymer blends was anticipated to result in fast in-situ compatibilization of immiscible blends. In order to test this hypothesis, a new ultrasonic extruder operating at a frequency of 20 kHz at amplitudes of 5, 7.5, and 10 mum was developed. Polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and wholly aromatic liquid crystalline copolyesters (LCPs) were selected to illustrate the effect of ultrasonic treatment on copolymerization of components through transesterification reactions in blends. The LCPs studied were a copolymer of hydroxybenzoic and hydroxynaphthoic acid (LCP1) and a copolymer of dioxydiphenyl, terephthalic and isophthalic acid (LCP2). PET/PEN, PET/LCP1, PEN/LCP1, and LCP1/LCP2 blends and their components were subsequently injection molded and spun into fibers. PET underwent homopolymerization and degradation, respectively, at ultrasonic amplitudes of 7.5 mum and 10 mum, while PEN underwent degradation at all amplitudes. MALDI-TOF mass spectroscopy revealed greater amounts of hydroxyl and carboxyl terminated oligomers in ultrasonically treated PET and PEN. Transesterification (copolymer formation) was observed in PET/PEN blends, which was enhanced with ultrasonic treatment, as indicated by 1H NMR and MALDI-TOF. Oxygen permeability of compression molded films of untreated and ultrasonically treated PET/PEN blends followed theoretical predictions for miscible blends. Ultrasonic treatment of LCP1 at amplitudes of 7.5 and 10 mum led to improved mechanical properties of its injection moldings. On the other hand, LCP2 underwent degradation with treatment, leading to a reduction of mechanical properties of LCP2 and LCP1/LCP2 blends. However, due to enhanced fibrillation, these blends retained synergism such that moldings exhibited

  14. Research Advance in Liquid Crystalline Polysaccharides and Their Applications%液晶性多糖的研究进展及其应用

    Institute of Scientific and Technical Information of China (English)

    高山俊; 张玲

    2009-01-01

    In this paper,liquid crystal polymer,its classifcation and characterization have been introduced. The study on liqiud crystalline polysaccharides is reviewed in detail,including cellulose and its derivatives,chitosan and its derivatives,xanthan,schizophyllan(SPG) and konjac glucomannan(KGM).The applications of liquid crystals of cellulose,chitosan and their derivatives are introduced.%介绍了高分子液晶及其分类和表征方法,综述了可以形成液晶的几种多糖,包括纤维素及其衍生物、壳聚糖及其衍生物、黄原胶、裂裥菌素(SPG)、魔芋葡苷聚糖(KGM)的研究进展,并对纤维素、壳聚糖及其衍生物液晶的应用进行了介绍.

  15. 1-D models for thin filaments of liquid-crystalline polymers: Coupling of orientation and flow in the stability of simple solutions

    Science.gov (United States)

    Gregory Forest, M.; Wang, Qi; Bechtel, Stephen E.

    Slender asymptotic fiber models are derived from Doi-type 3-D equations for free surface flows of liquid-crystalline polymers. Leading order equations and self-consistent corrections are presented for a variety of physical regimes. We then explore the coupling of orientation effects to slender elongational flow behavior, with particular focus on the interplay between the Rayleigh capillary instability and both stabilizing and destabilizing orientation behavior. In the simple context of constant solutions, we identify physical regimes and precise conditions under which the Rayleigh instability may be completely arrested, as well as other regimes where orientation reduces but does not cancel capillary instability. In addition, we identify sources of additional orientation-dominated instabilities that are evident in both the uniaxial and biaxial nematic liquid crystal order parameters. These models and stability analyses lay the foundation for applications to fiber spinning processes.

  16. Time- and Space-Resolved SAXS Experiments Inform on Phase Transition Kinetics in Hydrated, Liquid-Crystalline Films of Polyion-Surfactant Ion "Complex Salts".

    Science.gov (United States)

    Li, Joaquim; Gustavsson, Charlotte; Piculell, Lennart

    2016-05-24

    Detailed time- and space-resolved SAXS experiments show the variation with hydration of liquid crystalline structures in ethanol-cast 5-80 μm thick films of polyion-surfactant ion "complex salts" (CS). The CS were dodecyl- (C12) or hexadecyl- (C16) trimethylammonium surfactants with polyacrylate (DP 25 or 6000) counter-polyions. The experiments were carried out on vertical films in humid air above a movable water bath, so that gradients of hydration were generated, which could rapidly be altered. Scans over different positions along a film, kept fixed relative to the bath, showed that the surfactant aggregates of the various liquid-crystalline CS structures grow in cross-sectional area with decreasing hydration. This behavior is attributed to the low water content. Studies of films undergoing rapid dehydration, made possible by the original experimental setup, gave strong evidence that some of the investigated systems remain kinetically trapped for minutes in a nonequilibrium Pm3n micellar cubic phase before switching to the equilibrium P6mm 2D hexagonal phase. Both the length of the polyion and the length of the surfactant hydrocarbon "tail" affect the kinetics of the phase transition. The slowness of the cubic-to-hexagonal structural transition is attributed to the fact that it requires major rearrangements of the polyions and surfactant ions relative to each other. By contrast, other structure changes, such as between the hexagonal and rectangular phases, were observed to occur much more rapidly. PMID:27153140

  17. LINEARLY POLARIZED WHITE FLUORESCENCE FROM SHISH-KEBAB TYPE LIQUID CRYSTALLINE POLY(P-PHENYLENEVINVLENE)S WITH (P-PHENYLENE)S AS KEBAB

    Institute of Scientific and Technical Information of China (English)

    Kun Zhao; Jin-tao Wang; Cheng-zi Wang; Kai Li; Shi-jun Zheng; Kun Wang; Takaomi Kobayashi

    2012-01-01

    Liquid crystalline (LC) polymers with a shish-kebab-type moiety on their cross-conjugated (p-phenylene)s-poly(pphenylenevinylene)s main chains were synthesized through Gilch polymerization in order to develop a kind of polymers available for linearly polarized white-light-emitting from single chain.In this system,the 2,5-bis(4'-alkoxyphenyl)benzene as the “kebabs” connects with poly(p-phenylenevinylene) (PPV) main chain backbone using its molecular gravity center and the PPV as the “shish” or “skewer” (the “shish-kebab”).The polymers possess desirable properties such as excellent solubility and liquid crystalline properties.To drop the “kebabs” of the 2,5-bis(4'-alkoxyphenyl)benzene into the orientation microgroove of aligned polyimide film,not only the “shish” of polymer main chain can be aligned by the virtue of orientation of “kebabs” but also the uniform cross-conjugated structure between the “kebabs” and “shish” can be broken.Then,the alignment of the polymer main chain showed yellow light emission and was also accompanied by orientation of the LC side chains showing blue light emission,this gave rise to a notable linearly polarized white fluorescence.

  18. Pentadecyl phenol- and cardanol-functionalized fluorescent, room-temperature liquid-crystalline perylene bisimides: effect of pendant chain unsaturation on self-assembly.

    Science.gov (United States)

    Bhavsar, Ghanashyam A; Asha, S K

    2011-11-01

    A new perylene bisimide (PBI) building block based on pentadecyl phenol (PDP) or cardanol was developed, which upon esterification with 3,4,5-tridodecyloxy gallate resulted in highly emissive, room-temperature liquid-crystalline (LC) molecules. The self assembly in solution was studied in detail by NMR spectroscopy, UV/Vis absorption, and fluorescence spectroscopy. In solution both PDP- and cardanol-based PBI exhibited similar behavior. They were molecularly dissolved in chloroform (CHCl(3)) but formed rotationally displaced H-type aggregates that emitted at 640 nm in methylcyclohexane (MCH). Surface morphology in dropcast films were characterized using microscopic techniques such as SEM, TEM, and atomic force microscopy (AFM). The liquid-crystalline properties were studied using differential scanning calorimetry (DSC), polarized light microscopy (PLM), and variable-temperature X-ray (small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WXRD)) studies. Variable-temperature X-ray studies in the LC phase indicated strong π-π stacking interaction present in the PDP-based PBI derivative, whereas the stacking was absent in the LC phase of the cardanol-based PBI. The latter formed self-organized structures of extremely short length due to the presence of cis double bonds in the C15 alkyl side chain, whereas the saturated alkyl side chain in PDP could pack efficiently, thereby resulting in nanofibers that were several micrometers in length. PMID:21956257

  19. Retention behavior of polycyclic aromatic hydrocarbons in supercritical fluid chromatography on a chemically bonded stationary phases based upon liquid-crystalline polymer

    Energy Technology Data Exchange (ETDEWEB)

    Gritti [Bordeaux I Univ., Pessac (France). INSCPB; Bordeaux I Univ., Pessac (France). CRPP; Felix, G. [Bordeaux I Univ., Pessac (France). INSCPB; Achard, M.F.; Hardouin, F. [Bordeaux I Univ., Pessac (France). CRPP

    2001-02-01

    The retention behavior of a set of polycyclic hydrocarbons in supercritical fluid chromatography have been studied on a chemically bonded stationary phase based upon a side chain liquid crystalline polymer (LCP) with carbon dioxide-based mobile phase. The effects of the mobile phase pressure, column temperature and amount of mobile phase organic modifier have been investigated in order to detect a possible structural change in the liquid crystal polymer linked to the silica support. The influence of these factors on the selectivity coefficients has also been studied. Two distinctive behaviors with temperature are noted at low pressure on the one hand and at higher pressure on the other. This change in behavior is based on the density of the supercritical CO{sub 2} and the PAH volatility rather than on any specific stationary phase structural change. Both lower mobile phase pressure and amount of mobile phase modifier are required to obtain better selectivities. Better planarity recognition is observed in SFC than in HPLC with these new bonded liquid crystal stationary phases. The bonded liquid crystal phase is only weakly affected by the addition of organic modifier in the supercritical CO{sub 2}. (orig.)

  20. SYNTHESIS AND CHARACTERIZATION OF NOVEL CHIRAL SMECTIC C(Sc*) PHASE SHISH-KEBAB TYPE LIQUID CRYSTALLINE BLOCK COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    Shi-jun Zheng; Zi-fa Li; Shu-yuan Zhang; Shao-kui Cao; Ming-sheng Tang; Qiu-jun Fen; Qi-feng Zhou

    1999-01-01

    A new series of chiral shish-kebab type liquid crystal block copolymers that form the smectic C(Sc*) phase was synthesized by solution polycondensation. The copolymers were characterized by GPC,DSC, TG, POM, X-ray diffraction and polarimeter. The copolymers 7 entered into liquid crystal phase when they were heated to their melting temperatures (Tm) and the copolymers 8 were in liquid crystal phase at room temperature with low viscosities. The smectic sanded texture or focal-conic texture were observed on POM.All the chiral block copolymers showed high optical activity. No racemization has happened. Temperaturevariable X-ray diffraction study together with POM and polarimetric analysis realized that they are chiral smectic C(Sc*) phase. Thus we offer in this report the first example of shish-kebab type liquid crystal block copolymers that form a chiral smectic C(Sc*) phase. The variation of melting and isotropization temperatures with molecular structure was also discussed.

  1. Effect of electron irradiation on nanogroove-networked single-crystalline and dendritic polycrystalline platinum nanosheets prepared from lyotropic surfactant liquid-crystal templates

    International Nuclear Information System (INIS)

    Using transmission electron microscopy (TEM) electron irradiation effects were studied for nanogroove-network structured single-crystalline and dendritic polycrystalline Pt nanosheets 50-60 nm in size. These two nanosheets with nearly the same average groove-width or dendritic spacing of 1.3-1.4 nm were prepared from the mixed and single surfactant liquid crystalline templates, respectively. On exposure to electron beam for 20 min at the acceleration voltage of 200 kV, the nanogrooved nanosheets were morphologically little affected, but the dendritic ones were transformed into less branched polycrystalline structures with spacings distributed around ∼1.7 nm. The shape transformation of the latter occurred by the combined mechanism of segmental migration and atomic diffusion. These observations indicate that the nanogrooved Pt nanosheets are highly stabilized by the grooved but crystallographically continuous Pt framework, leading to their extremely high thermo-resistance, in marked contrast to the polycrystalline dendritic structures constructed of crystallographically discontinuous linkages of nanoblocks

  2. EFFECT OF DRAWING ON MORPHOLOGY,STRUCTURE AND MECHANICAL PROPERTIES OF BLENDS OF A LIQUID CRYSTALLINE POLYMER AND MODIFIED POLY(PHENYLENE OXIDE)

    Institute of Scientific and Technical Information of China (English)

    LIU Songlin; SHEN Jingshu

    1997-01-01

    Polymer strands with various draw ratios of a thermotropic liquid crystalline polymer (LCP) and modified poly(phenylene oxide) were prepared by drawing the melts leaving a slit die in open air. The morphology, structure and mechanical properties of the resulting strands were studied as a function of LCP content and draw ratio. It was found that the thermal and mechanical properties of the matrix phase did not change dramatically with the amount of LCP and draw ratio, but the orientation of LCP phase could be increased with draw ratio. The mechanical properties of the strands could be improved by moderately drawing the melts. Wide angle X-ray diffraction suggested that the improvement in tenile strength of the strands was due to the resultant fibrillation of LCP phase and enhanced molecular orientation. Morphological observation indicated that excessive drawing of the strands could lead to the break down of the microfibrils of LCP and thus resulted in the decrease of mechanical strength.

  3. Controlling the color of cholesteric liquid-crystalline films by photoirradiation of a chiroptical molecular switch used as dopant

    NARCIS (Netherlands)

    van Delden, RA; Huck, NPM; Feringa, BL; Delden, Richard A. van; Gelder, Marc B. van; Huck, Nina P.M.

    2003-01-01

    Using thin films of a cholesteric mixture of acrylates 2 and 3 doped with the chiroptical molecular switch (M)-trans-1, photo-control of the reflection color between red and green is possible. This doped liquid-crystal (LC) film can be used for photoinduced writing, color reading, and photoinduced l

  4. Liquid-crystalline polyesters with end nitroxyl radical and their use in living free-radical polymerization

    Czech Academy of Sciences Publication Activity Database

    Razina, A B.; Sedláková, Zdeňka; Bouchal, Karel; Tenkovtsev, A. V.; Ilavský, Michal

    2002-01-01

    Roč. 44, č. 9 (2002), s. 924-930. ISSN 0965-545X R&D Projects: GA AV ČR KSK4050111 Institutional research plan: CEZ:AV0Z4050913 Keywords : liquid crystal * polyesters * nitroxyl radical Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.627, year: 2002

  5. Vapor-deposited non-crystalline phase vs ordinary glasses and supercooled liquids: Subtle thermodynamic and kinetic differences

    International Nuclear Information System (INIS)

    Vapor deposition of molecules on a substrate often results in glassy materials of high kinetic stability and low enthalpy. The extraordinary properties of such glasses are attributed to high rates of surface diffusion during sample deposition, which makes it possible for constituents to find a configuration of much lower energy on a typical laboratory time scale. However, the exact nature of the resulting phase and the mechanism of its formation are not completely understood. Using fast scanning calorimetry technique, we show that out-of-equilibrium relaxation kinetics and possibly the enthalpy of vapor-deposited films of toluene and ethylbenzene, archetypical fragile glass formers, are distinct from those of ordinary supercooled phase even when the deposition takes place at temperatures above the ordinary glass softening transition temperatures. These observations along with the absolute enthalpy dependences on deposition temperatures support the conjecture that the vapor-deposition may result in formation of non-crystalline phase of unique structural, thermodynamic, and kinetic properties

  6. Vapor-deposited non-crystalline phase vs ordinary glasses and supercooled liquids: Subtle thermodynamic and kinetic differences

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharya, Deepanjan; Sadtchenko, Vlad, E-mail: vlad@gwu.edu [Chemistry Department, The George Washington University, Washington, DC 20052 (United States)

    2015-04-28

    Vapor deposition of molecules on a substrate often results in glassy materials of high kinetic stability and low enthalpy. The extraordinary properties of such glasses are attributed to high rates of surface diffusion during sample deposition, which makes it possible for constituents to find a configuration of much lower energy on a typical laboratory time scale. However, the exact nature of the resulting phase and the mechanism of its formation are not completely understood. Using fast scanning calorimetry technique, we show that out-of-equilibrium relaxation kinetics and possibly the enthalpy of vapor-deposited films of toluene and ethylbenzene, archetypical fragile glass formers, are distinct from those of ordinary supercooled phase even when the deposition takes place at temperatures above the ordinary glass softening transition temperatures. These observations along with the absolute enthalpy dependences on deposition temperatures support the conjecture that the vapor-deposition may result in formation of non-crystalline phase of unique structural, thermodynamic, and kinetic properties.

  7. Thermotropic and lyotropic behaviour of new liquid-crystalline materials with different hydrophilic groups: synthesis and mesomorphic properties

    Czech Academy of Sciences Publication Activity Database

    Bubnov, Alexej; Kašpar, Miroslav; Hamplová, Věra; Dawin, U.; Giesselmann, F.

    2013-01-01

    Roč. 9, FEB (2013), s. 425-436. ISSN 1860-5397 R&D Projects: GA ČR(CZ) GAP204/11/0723 Grant ostatní: AVČR(CZ) M100101204; AVČR(CZ) M100101211; FASI(RU) RFASI 02.740.11.5166; AV ČR-DAAD SNR(CZ) D4-CZ5/2010-2011 Institutional support: RVO:68378271 Keywords : thermotropic liquid crystals * lyotropic liquid crystals * contact cell preparation * X-ray scattering * hydrophilic chains * lamellar phase Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.803, year: 2013 http://www. beilstein - journal s.org/bjoc/single/articleFullText.htm?publicId=1860-5397-9-45

  8. Chiral HPLC for a study of the optical purity of new liquid crystalline materials derived from lactic acid

    Czech Academy of Sciences Publication Activity Database

    Vojtylová, Terézia; Kašpar, Miroslav; Hamplová, Věra; Novotná, Vladimíra; Sýkora, D.

    2014-01-01

    Roč. 87, č. 8 (2014), s. 758-769. ISSN 0141-1594 R&D Projects: GA ČR GA13-14133S Institutional support: RVO:68378271 Keywords : lactic acid derivative * smectic phase * high performance liquid chromatography * chiral separation Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 0.954, year: 2014 http://www.tandfonline.com/doi/abs/10.1080/01411594.2014.893344#.VGxWfVeNrcs

  9. Structures of bulk amorphous Zr41Ti14Ni10Cu12.5Be22.5 alloy in amorphous, crystalline, supercooled liquid and liquid states

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The amorphous and crystal structures of Zr41Ti14Ni10Cu12.5Be22.5 alloy have been analyzed with X-ray diffractometer. The structures of bulk amorphous Zr41Ti14Ni10Cu12.5B22.5 alloy in solid, supercooled liquid and liquid states are almost of the same structure. The RDFs (Radius Distribution Function), the first coordination number, the first coordination radius, the correlation radius and atom number of the cluster were calculated for bulk amorphous Zr41Ti14Ni10Cu12.5B22.5 alloy in different states. The first coordination sphere radii and the first coordination numbers are 0.312nm, 11.2 in solid state, 0.301nm, 10.932 in supercooled liquid region and 0.305nm, 11.296 in liquid state. The crystal structure of Zr41Ti14Ni10Cu12.5B22.5 alloy is consisted of several intermetallic compounds which are CuZr2, Be2Zr, etc. The reason of formation glass for this alloy is that there is a larger resistance for atoms to rearrange and form intermetallic compounds in a long range order.

  10. The In Vitro Lipolysis of Lipid-Based Drug Delivery Systems: A Newly Identified Relationship between Drug Release and Liquid Crystalline Phase

    Science.gov (United States)

    Xiao, Lu; Yi, Tao; Liu, Ying; Zhou, Hua

    2016-01-01

    The purpose of this study was to offer a new insight into the microstructure changes during in vitro lipolysis of five lipid-based drug delivery formulations belonging to different lipid formulation types. Five lipid-based formulations of indomethacin were investigated using an in vitro lipolysis model. During lipolysis, microstructures of the intermediate phase formed by lipolytic products were observed. The results showed that the time of liquid crystal formation during in vitro digestion for these formulations was Type I > Type II > Type IIIB > Type IV > Type IIIA (p lipolysis, the drug releases from these formulations were determined. The results showed that the amount of drug distributed in the aqueous phase, obtained by ultracentrifuge after lipolysis, was, astonishingly, in inverse rank order of the above mentioned, that is, Type IIIA > Type IV > Type IIIB > Type II > Type I (p lipolysis and suggested that the liquid crystalline phase facilitated drug precipitation. These findings may improve the understanding of lipolysis of lipid-based drug delivery systems for designing better delivery system. PMID:27294110

  11. Synthesis, characterization and electro-optic properties of novel siloxane liquid crystalline with a large tilt angle

    International Nuclear Information System (INIS)

    Research highlights: → In this study we report the synthesis and characterization of new ferroelectric liquid crystal material. → We examined the influence of the addition of a trisiloxane end-group on one side-chain of an achiral alkyl chain on the phase transition. → Finally, the properties of the chiral smectic C (SmC*) phase were measured for target compounds. - Abstract: This paper presents a study of the ferroelectric behavior in low molar mass organosiloxane liquid crystal materials. A few novel series of compounds with a large tilt angle were synthesized, and the mesophases exhibited were compared. The mesophases under discussion were investigated by means of polarizing microscopy (POM), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and electro-optical experiments. The influence of the molecular structure on the occurrence of the chiral smectic C (SmC*) phase was investigated. Finally, the electro-optical properties of the SmC* phase, such as tilt angle, dielectric permittivity and switching behavior were also measured. As a consequence, the correlation between the electro-optical properties and chemical structures of these compounds was investigated.

  12. 一种液晶聚氨酯的合成及应用%Synthesis and Application of A Liquid Crystalline Polyurethanes

    Institute of Scientific and Technical Information of China (English)

    班建峰; 陆绍荣; 于春贺; 黄志义; 刘括

    2011-01-01

    The main-chain liquid-crystalline polyurethane(PLCP) was synthesized by the solvent copolymerization of hydroquinone,para hydroxy benzoic acid,toluenediisocyanate(TDI) and trithylene glycol,then the liquid crystalline properties was characterized by means of Fourier transformed infrared spectroscopy(FT-IR),polarized optical microscope(POM),and wide-angle X-ray diffraction(WAXD).It shows that this compound is nematic liquicl crystal texture.The mechanical properties,thermal properties and microscopic fracture surface morphology of the PLCP toughened epoxy resin were investigated.Experimental results show that the impact strength of composites is two times higher than that of the unmodified system when the content of PLCP loading reaches 3%.In addition,the thermal decomposition temperature is also 5 ℃~10 ℃ higher than that of the unmodified system.%以对苯二酚、对羟基苯甲酸、甲苯二异氰酸酯(2,4-TDI)和二缩三乙二醇等为原料,采用溶液聚合的方法,共缩聚合成具有液晶性的主链型聚氨酯(PLCP),并采用傅里叶红外光谱(FT-IR)、偏光显微镜(POM)及广角X射线衍射(WAXD)等对其结构进行了表征,研究证实该化合物为向列型液晶。研究了PLCP增韧改性环氧树脂固化体系的力学性能、热性能及断裂面的微观形态结构,结果表明,PLCP质量分数为3%可使材料的冲击强度提高近2倍,热分解温度提高5℃~10℃。

  13. Photo-stimulated electro-optic response of liquid-crystalline system with trans-cis photo-isomerizable agent

    International Nuclear Information System (INIS)

    A rather strong photo-stimulated enhancement of photo-induced bend flexoelectric effect based on trans-cis photoisomerization of azo bond was found in a guest-host system formed from the nematic liquid crystal (LC) N-(4-methoxybenzylidene)-4-butylaniline (MBBA) as a host, and the azobenzene LC 4-hexyloxybenzoloxy-4'-cyanoazobenzene, as a guest photoactive agent at 1 wt.% concentration. Upon application of electric field, thin homeotropic layers of thickness 100 pm containing this photo-sensitized LC mixture were investigated as subjected to a relatively weak illumination with UV light (λ = 375 nm, from narrow-band light-emitting diode, LED). The stimulation of the photoactive electro-optic response of azobenzene-doped MBBA (owing to enhanced photo-induced bend flexoelectric effect driven by the photo-isomerizable dopants) was achieved by pre-resonant excitation of the photoactive agent. The degree of the effect measured is of potential interest for thin-film photoactive electro-optic applications. The UV light-induced effect in azobenzene-doped MBBA was reversible; the back (relaxation) process was stimulated by light in the blue from a LED with broadband spectrum centered at 455 nm

  14. Improved cross validation of a static ubiquitin structure derived from high precision residual dipolar couplings measured in a drug-based liquid crystalline phase.

    Science.gov (United States)

    Maltsev, Alexander S; Grishaev, Alexander; Roche, Julien; Zasloff, Michael; Bax, Ad

    2014-03-12

    The antibiotic squalamine forms a lyotropic liquid crystal at very low concentrations in water (0.3-3.5% w/v), which remains stable over a wide range of temperature (1-40 °C) and pH (4-8). Squalamine is positively charged, and comparison of the alignment of ubiquitin relative to 36 previously reported alignment conditions shows that it differs substantially from most of these, but is closest to liquid crystalline cetyl pyridinium bromide. High precision residual dipolar couplings (RDCs) measured for the backbone (1)H-(15)N, (15)N-(13)C', (1)H(α)-(13)C(α), and (13)C'-(13)C(α) one-bond interactions in the squalamine medium fit well to the static structural model previously derived from NMR data. Inclusion into the structure refinement procedure of these RDCs, together with (1)H-(15)N and (1)H(α)-(13)C(α) RDCs newly measured in Pf1, results in improved agreement between alignment-induced changes in (13)C' chemical shift, (3)JHNHα values, and (13)C(α)-(13)C(β) RDCs and corresponding values predicted by the structure, thereby validating the high quality of the single-conformer structural model. This result indicates that fitting of a single model to experimental data provides a better description of the average conformation than does averaging over previously reported NMR-derived ensemble representations. The latter can capture dynamic aspects of a protein, thus making the two representations valuable complements to one another. PMID:24568736

  15. Effects of phospholipid hydrolysis on the aggregate structure in DPPC/DSPE-PEG2000 liposome preparations after gel to liquid crystalline phase transition.

    Science.gov (United States)

    Ickenstein, Ludger M; Sandström, Maria C; Mayer, Lawrence D; Edwards, Katarina

    2006-02-01

    Upon storage of phospholipid liposome samples, lysolipids, fatty acids, and glycerol-3-phosphatidylcholine are generated as a result of acid- or base-catalyzed hydrolysis. Accumulation of hydrolysis products in the liposome membrane can induce fusion, leakage, and structural transformations of the liposomes, which may be detrimental or beneficial to their performance depending on their applications as, e.g., drug delivery devices. We investigated in the present study the influence of phospholipid hydrolysis on the aggregate morphology of DPPC/DSPE-PEG2000 liposomes after transition of the phospholipid membrane from the gel phase to liquid crystalline phase using high performance liquid chromatography (HPLC) in combination with static light scattering, dynamic light scattering, and cryo-transmission electron microscopy (cryo-TEM). The rates of DPPC hydrolysis in DPPC/DSPE-PEG2000 liposomes were investigated at a pH of 2, 4, or 6.5 and temperatures of 22 degrees C or 4 degrees C. Results indicate that following phase transition, severe structural reorganizations occurred in liposome samples that were partially hydrolyzed in the gel phase. The most prominent effect was an increasing tendency of liposomes to disintegrate into membrane discs in accordance with an increasing degree of phospholipid hydrolysis. Complete disintegration occurred when DPPC concentrations had decreased by, in some cases, as little as 3.6%. After extensive phospholipid hydrolysis, liposomes and discs fused to form large bilayer sheets as well as other more complex bilayer structures apparently due to a decreased ratio of lysolipid to palmitic acid levels in the liposome membrane. PMID:16574061

  16. Intense pulsed light induced crystallization of a liquid-crystalline polymer semiconductor for efficient production of flexible thin-film transistors.

    Science.gov (United States)

    Yang, Hee Yeon; Park, Han-Wool; Kim, Soo Jin; Hong, Jae-Min; Kim, Tae Whan; Kim, Do Hwan; Lim, Jung Ah

    2016-02-14

    Here we demonstrated the split-second crystallization of a liquid-crystalline conjugated polymer semiconductor induced by irradiation with intense pulsed white light (IPWL) for the efficient improvement of electrical properties of flexible thin film transistors. A few seconds of IPWL irradiation of poly(didodecylquaterthiophene-alt-didodecylbithiazole) (PQTBTz-C12) thin films generated heat energy through the photo-thermal effect, leading to the crystallization of PQTBTz-C12 and formation of nodule-like nanostructures. The IPWL-induced crystallization of PQTBTz-C12 resulted in a threefold improvement in the field-effect mobility of thin film transistors compared to as-prepared devices. The conformational change of the PQTBTz-C12 chains was found to be strongly related to the irradiation fluence. As a proof-of-concept, the IPWL treatment was successfully applied to the PQTBTz-C12 layer in flexible transistors based on plastic substrates. The performance of these flexible devices was significantly improved after only 0.6 s of IPWL treatment, without deformation of the plastic substrate. PMID:26795202

  17. Synthesis and Characterisation of Photo-Cross-Linkable Liquid Crystalline Poly(n-[n′-flurobenzoylstyryloxy]alkylmethacrylates and Their Fluorescence Lifetime Properties

    Directory of Open Access Journals (Sweden)

    G. Kumar

    2013-01-01

    Full Text Available This paper reports a study on photo-cross-linkable polymer containing pendant chalcone moiety exhibiting liquid crystalline as well as fluorescence lifetime properties in detail. The photoresponsive polymers were prepared, and their structure has been characterized by 1H-NMR, 13C-NMR, and UV-Visible spectroscopy. The photo-cross-linking behavior of polymers has been studied by UV-Visible and fluorescence spectroscopy. UV spectral studies revealed that the polymers follow 2π+2π cyclo addition reactions when they undergo photo-cross-linking under the influence of UV-light. Number and weight average molecular weight of the polymers were determined by Gel Permeation Chromatography (GPC and polydispersity index value near to 1.5. The thermal and thermooxidative stability of the polymers were determined by Thermogravimetric Analysis (TGA. Thermal transitions were studied by DSC, and presence of mesophases was identified at 147 and 126∘C by hot stage polarized light optical microscopy (HPOM. Fluorescence lifetime measurements using the time-correlated single photon counting (TCSPC method reveal that the average lifetime values decrease from 5.94 ns to 5.32 ns on UV-irradiation were discussed in detail.

  18. Estimation of activation energy for electroporation and pore growth rate in liquid crystalline and gel phases of lipid bilayers using molecular dynamics simulations.

    Science.gov (United States)

    Majhi, Amit Kumar; Kanchi, Subbarao; Venkataraman, V; Ayappa, K G; Maiti, Prabal K

    2015-11-28

    Molecular dynamics simulations of electroporation in POPC and DPPC lipid bilayers have been carried out at different temperatures ranging from 230 K to 350 K for varying electric fields. The dynamics of pore formation, including threshold field, pore initiation time, pore growth rate, and pore closure rate after the field is switched off, was studied in both the gel and liquid crystalline (Lα) phases of the bilayers. Using an Arrhenius model of pore initiation kinetics, the activation energy for pore opening was estimated to be 25.6 kJ mol(-1) and 32.6 kJ mol(-1) in the Lα phase of POPC and DPPC lipids respectively at a field strength of 0.32 V nm(-1). The activation energy decreases to 24.2 kJ mol(-1) and 23.7 kJ mol(-1) respectively at a higher field strength of 1.1 V nm(-1). At temperatures below the melting point, the activation energy in the gel phase of POPC and DPPC increases to 28.8 kJ mol(-1) and 34.4 kJ mol(-1) respectively at the same field of 1.1 V nm(-1). The pore closing time was found to be higher in the gel than in the Lα phase. The pore growth rate increases linearly with temperature and quadratically with field, consistent with viscosity limited growth models. PMID:26372335

  19. ACCESSIBILITY AND CRYSTALLINITY OF CELLULOSE

    Directory of Open Access Journals (Sweden)

    Michael Ioelovich

    2009-08-01

    Full Text Available The accessibility of cellulose samples having various degrees of crystallinity was studied with respect to molecules of water, lower primary alcohols, and lower organic acids. It was found that small water molecules have full access to non-crystalline domains of cellulose (accessibility coefficient α = 1. Molecules of the lowest polar organic liquids (methanol, ethanol, and formic acid have partial access into the non-crystalline domains (α<1, and with increasing diameter of the organic molecules their accessibility to cellulose structure decreases. Accessibility of cellulose samples to molecules of various substances is a linear function of the coefficient α and the content of non-crystalline domains. The relationship between crystallinity (X and accessibility (A of cellulose to molecules of some liquids has been established as A = α (1-X. The water molecules were found to have greater access to cellulose samples than the molecules of the investigated organic liquids. The obtained results permit use of accessibility data to estimate the crystallinity of cellulose, to examine the structural state of non-crystalline domains, and to predict the reactivity of cellulose samples toward some reagents.

  20. Synthesis and characterization of novel liquid-crystalline azo-dyes bearing two amino-nitro substituted azobenzene units and a well-defined, oligo(ethylene glycol) spacer

    International Nuclear Information System (INIS)

    Highlights: → Novel dyes containing azobenzene and oligo(ethylene glycol) were synthesized. → Absorption spectra of RED-PEG dyes in CHCl3 showed λmax = 440-480 nm. → Absorption spectra of RED-PEG dyes in film revealed the formation of H-aggregates. → Their liquid-crystalline behaviour was confirmed by light polarized microscopy. → These liquid-crystalline dyes can form Langmuir films on the air-water interface. - Abstract: Four novel liquid-crystalline azo-dyes bearing two amino-nitro substituted azobenzene units linked by a well-defined oligo(ethylene glycol) spacer (DIRED-PEG series): (E)-N,N'-(2,2'-oxybis(ethane-2,1-diyl))bis(N-methyl-4-((E)-(4-nitrophenyl) diazenyl) benzenamine) (DIRED-PEG-2), (E)-N,N'-(2,2'-(ethane-1,2-diylbis(oxy)) bis(ethane-2,1-diyl)) bis(N-methyl-4-((E)-(4-nitrophenyl) diazenyl) benzenamine) (DIRED-PEG-3), (E)-N,N'-(2,2'-(2,2'-oxybis (ethane-2,1-diyl) bis(oxy)) bis(ethane-2,1-diyl)) bis(N-methyl-4-((E)-(4-nitrophenyl) diazenyl) benzenamine) (DIRED-PEG-4) and N1,N17-dimethyl-N1,N17-bis (4-((E)-(4-nitrophenyl) diazenyl) phenyl)-3,6,9,12,15-pentaoxaheptadecane-1,17-diamine (DIRED-PEG-6) have been synthesized. These dyes were fully characterized by FTIR, 1H and 13C NMR spectroscopies, and their thermal and optical properties were studied. Besides, the liquid-crystalline behaviour of these compounds was monitored in function of the temperature by light polarized microscopy. Finally, Langmuir films were prepared with these dyes.

  1. Columnar liquid-crystalline dinaphthoperylenetetracarboxdiimides.

    Science.gov (United States)

    Ferreira, Marli; Girotto, Edivandro; Bentaleb, Ahmed; Hillard, Elizabeth A; Gallardo, Hugo; Durola, Fabien; Bock, Harald

    2015-03-01

    Although the double Friedel-Crafts acylation of arenes with ethyl chloroglyoxylate is hindered by the strongly deactivating effect of the first-entering glyoxylic substituent, the double reaction is successful with the reactive arene perylene under long reaction times and with concomitant ester hydrolysis. The reaction is regiospecific, giving the 3,9-regioisomer exclusively. This perylenylenediglyoxylic acid is condensed first with o-bromophenylacetic acid and then with α-branched alkylamines to yield the title compounds. Whilst the corresponding tetraalkyl esters only show monotropic mesophases, these diimides show enantiotropic columnar mesophases that can be maintained at room temperature if racemically branched alkyl chains of moderate size are used. A palladium-induced C-C bond migration during the build-up of the arene system leads to an isomeric side product of reduced symmetry that can be isolated by aggregation-controlled chromatographic separation. The HOMO and LUMO energies of the title compounds are considerably higher than those of established perylenetetracarboxdiimides. PMID:25656752

  2. Synthesis and Characterization of Ferroelectric Liquid Crystalline Organosiloxanes Containing 4-(4-undecanyloxy bi-phenyl-1-carboxyloxyphenyl (2S,3S-2-chloro-3-methylvalerate and 4-(4-undecanyloxybenzoyloxybiphenyl (2S,3S-2-chloro-3-methylvalerate

    Directory of Open Access Journals (Sweden)

    Chih-Hung Lin

    2013-10-01

    Full Text Available A series of new organosiloxane ferroelectric liquid crystalline (FLC materials have been synthesized, and their mesomorphic and physical properties have been characterized. Four new disiloxanes and trisiloxanes, containing biphenyl 4-hydroxybenzoate and phenyl 4-hydroxybiphenylcarboxylate as mesogenic units and eleven methylene unit as spacers and (2S,3S-2-chloro-3-methylvalerate unit as chiral end groups. The molecule, using three phenyl ring as a mesogenic unit, formulates much wider liquid crystalline phase temperature ranges than that of a two phenyl ring unit. The phenyl arrangement differences of mesogenic unit result in the greater differences of the liquid crystal phase formation. The siloxane molecule induction is helpful to the more regular smectic phase formation and smectic phase stabilization, such as chiral SC (SC* and SB phases. The siloxane molecule is helpful to reduce the phase transition temperature and broaden the liquid crystal temperature range of the SC* phase and, simultaneously, it will not induce chain crystallization phenomenon and dilute the Ps value. The synthesis and characterization of the new FLCs materials, which exhibit a room temperature SC* phase and higher spontaneous polarization are presented.

  3. PHASE STRUCTURE AND THERMAL BEHAVIOR OF LIQUID CRYSTALLINE MULTI-BLOCK COPOLYMERS,POLY[1,6-BIS(4-OXYBENZOYL-OXY)HEXANE TEREPHTHALATE]-b-BISPHENOL A POLYCARBONATE

    Institute of Scientific and Technical Information of China (English)

    Hui-qing Zhang; Xiong-yan Zhao; De-shan Liu; Qi-xiang Zhou

    1999-01-01

    Liquid crystalline multi-block copolymers poly[1,6-bis(4-oxybenzoyl-oxy)hexane terephthalate]-b-bisphenol A polycarbonate (PHTH-6-b-PC) with different segments of polycarbonate (PC) and thermotropic polyester PHTH-6 were synthesized in tetrachloroethane at 144~146℃. The influence of segment length on the resulting phase structure and thermal behavior of block copolymers was also discussed. It is demonstrated by TEM and DMA that the resulting block copolymers show a considerable microphase separation. The degree of phase separation and the thermal behavior of the block copolymers are strongly dependent on the molecular weight of the segments incorporated.

  4. 1,3-Dimethyl-5-(3,4,5-tris(alkoxy)benzoyl) barbituric acid derivatives and their liquid crystalline difluoroboron complexes: Synthesis, characterization and comparative investigations of mesomorphic, thermotropic and thermo-morphologic properties

    Science.gov (United States)

    Giziroglu, Emrah; Nesrullajev, Arif; Orhan, Nil

    2014-01-01

    A series of 1,3-dimethyl-5-(3,4,5-tris(alkoxy)benzoyl) barbituric acid derivatives 1a-4a with various chain length were synthesized by our group for the first time through the addition of 1,3-dimethyl barbituric acid to 3,4,5-tris(alkoxy)benzoyl chloride at room temperature in presence of pyridine. For preparation of their difluoroboron complexes, the derivatives 1a-4a reacts with borontrifluoride in the presence of triethylamine affording 1b-4b in moderate yields. All derivatives and complexes have been fully characterized by MS, FT-IR and multinuclear NMR spectroscopy. We also explored their liquid crystal properties by using POM, OM, CTW and DSC techniques. The results show that 3b and 4b with longer alkyl chain are monomorphic mesogens and exhibited enantiotropic thermotropic liquid crystalline mesophases. Investigation of their mesomorphic, thermo-morphologic and thermotropic properties is presented in this work.

  5. Microwave-assisted ionic-liquid-based synthesis of highly crystalline CaMoO4:RE3+ (RE = Tb, Sm, Eu) and Y2Mo4O15:Eu3+ nanoparticles

    Science.gov (United States)

    Kuzmanoski, Ana; Pankratov, Vladimir; Feldmann, Claus

    2015-03-01

    Fluorescent CaMoO4:RE3+ (RE = Tb, Sm, Eu) nanoparticles, 50-70 nm in diameter, were prepared via a microwave-assisted synthesis in ionic liquids. Herein, the ionic liquid allows heating to high temperatures in the liquid phase (200 °C), which guarantees for an optimal crystallization of the nanoparticles. All nanoparticles were indeed readily crystalline without the need of any additional powder sintering. Especially, CaMoO4:Tb and CaMoO4:Eu exhibit high quantum yields of 52% and 82% under UV-excitation (300-320 nm). All compounds were characterized by electron microscopy (SEM), dynamic light scattering (DLS), infrared spectroscopy (FT-IR), energy-dispersive X-ray analysis (EDX), X-ray diffraction (XRD), and fluorescence spectroscopy (FL). In order to shift the excitation to even higher wavelengths, Y2Mo4O15:Eu was firstly realized as a nanomaterial, again, using the microwave-assisted synthesis in ionic liquids. Y2Mo4O15:Eu exhibits a particle size of 25-30 nm, and shows a high quantum yield of 67%, too. As this nanomaterial can be excited up to 400 nm, it represents one of the first efficient red-emitting, Eu3+-doped nanomaterials for near-UV excitation (>350 nm) with a simple, low-cost UV-LED. This can be relevant for all kinds of thin-film applications as well as for optical imaging.

  6. Liquid Crystalline Nanodispersions Functionalized with Cell-Penetrating Peptides for Topical Delivery of Short-Interfering RNAs: A Proposal for Silencing a Pro-Inflammatory Cytokine in Cutaneous Diseases.

    Science.gov (United States)

    Petrilli, R; Eloy, J O; Praça, F S G; Del Ciampo, J O; Fantini, M A C; Fonseca, M J V; Bentley, M V L B

    2016-05-01

    Short-interfering RNAs (siRNAs) are a potential strategy for the treatment of cutaneous diseases. In this context, liquid crystalline nanoparticles functionalized with specific proteins and peptide-transduction domains (PTDs), which act as penetration enhancers, are a promising carrier for siRNA delivery through the skin. Herein, hexagonal phase liquid crystal nanoparticles based on monoolein (MO) and/or oleic acid (OA) containing (or lacking) the cationic polymer polyethylenimine (PEI) and the cationic lipid oleylamine (OAM) were functionalized with the membrane transduction peptides transcriptional activator (TAT) or penetratin (PNT). These nanoparticles were complexed with siRNA and characterized by particle size, polydispersity, zeta potential, complexation efficiency and siRNA release. The formulations containing cationic agents presented positive zeta potentials, sizes on the nanometer scale, and complexed siRNAs at concentrations of 10 μM; these agents were successfully released in a heparin competition assay. Cell culture studies demonstrated that nanoparticles composed of MO:OA:PEI functionalized with TAT were the most efficient at transfecting L929 cells, and the uptake efficiency was enhanced by TAT peptide functionalization. Thereafter, the selected formulations were evaluated for in vivo skin irritation, penetration and in vivo efficacy using a chemically induced inflammatory animal model. These nanoparticles did not irritate the skin and provided higher siRNA penetration and delivery into the skin than control formulations. Additionally, efficacy studies in the animal model showed that the association of TAT with the nanodispersion provided higher suppression of tumor necrosis factor (TNF)-α. Thus, the development of liquid crystalline nanodispersions containing TAT may lead to improved topical siRNA delivery for the treatment of inflammatory skin diseases. PMID:27305826

  7. Preparation and Properties of Liquid Crystalline Polyester / Epoxy Resin Composites%聚酯液晶/环氧树脂复合材料的合成及应用

    Institute of Scientific and Technical Information of China (English)

    刘括; 陆绍荣; 罗崇禧; 李善荣; 郭栋

    2013-01-01

    以4,4'-二(β-羟乙氧基)联苯(BP2)、对苯二甲酰氯(TPC)为原料,吡啶为催化剂,通过溶液聚合法合成一种含有联苯基的新型聚酯液晶(DCLP).采用红外光谱(FT-IR)、偏光显微镜(POM)及X射线衍射(WAXD)对DCLP的分子结构和液晶性进行表征,然后将该聚酯液晶与环氧树脂(E-44)共混制备聚酯液晶/环氧树脂复合材料,并对其性能进行研究.实验结果表明,加入3%的DCLP,可使复合材料的冲击强度由26.2kJ/m2提高到47.7kJ/m2,拉伸强度和弯曲强度也有不同程度的提高,热分解温度提高10℃~20℃.冲击断面的扫描电镜(SEM)分析表明,聚酯液晶对环氧树脂固化物有明显的增韧效果.%Using pyridine as catalyst,a new kind of liquid crystalline polyester (DCLP) containing diphenylnate was synthesized by solution polymerization of 4,4'-bis-(2-hydroxyhexoxy)biphenyl (BP2) and paraphthaloyl chloride,then characterized by means of FT-IR,POM and WAXD.The observation of POM shows that the liquid crystalline polyester is a thermotropic nematic liquid crystalline polymer.The properties of DCLP were characterized.DCLP was used to modify the conventional epoxy resin (E-44).Experimental results reveal that the impact strength of the epoxy resin modified with DCLP increases from 26.2 kJ/m2 to 47.7 kJ/m2,and the tensile strength as well as the bending strength is also improved.The thermal decomposition temperature of modified systems is also 10 ℃ ~20 ℃ higher than that of the unmodified system.The SEM micrographs of impact fracture show that cured product of epoxy has a significant toughening effect.

  8. SYNTHESIS AND CURING OF A NOVEL LIQUID CRYSTALLINE EPOXY RESIN%一种新型液晶环氧树脂的合成表征与固化研究

    Institute of Scientific and Technical Information of China (English)

    王海梅; 张越超; 朱丽荣; 张育英; 张保龙

    2011-01-01

    首次合成了一种不对称联苯和芳香酯型液晶环氧树脂4"-环氧丙氧基苯甲酸-4-环氧丙氧基联苯-4'-酯(EBEPC),利用FT-IR、1H NMR、DSC和POM对其结构和性能进行了表征.结果表明,EBEPC在190℃时可形成明显的向列相液晶.对其同普通固化剂DDM体系的固化反应过程、固化动力学进行了研究,与普通环氧树脂E-51/DDM体系比较,液晶环氧树脂EBEPC体系具有较低的固化反应温度,且表观话化能Ea(54.5kJ/mol)较E-51/DDM体系(60.7kJ/mol)低,EBEPC体系具有更高的反应活性.%A novel liquid crystalline epoxy resin containing biphenyl and aromatic ester-type structure 4-(2,3-epoxypropoxy)biphenyl,4”-(2,3-epoxypropoxy)phenyl-4'carboxylate (EBEPC)was synthesized. The structure and phase behavior of the synthesized product were characterized by means of IR, 1H NMR, DSC and POM. The result showed that a clear single axis homeotropic nematic droplet texture was obtained. The liquid crystalline epoxy resin was cured with a curing agent diaminodiphenylmethane (DDM). The results displayed that EBEPC/DDM system had a lower curing reaction temperature than the ordinary epoxy resin E-51 system which was also cured by DDM, and the apparent activation energy (Ea) of liquid crystalline epoxy resin system (54.5kJ/mol) was lower than E-51 system (60.7kJ/mol). It indicated that the EBEPC system had higher reaction activity than the E-51 system.

  9. Electric properties of hyperbranch liquid crystalline/Al2O3/epoxy resin composites%超支化液晶/Al2O3/环氧树脂复合材料电性能研究

    Institute of Scientific and Technical Information of China (English)

    班建峰; 庞起; 梁春杰; 覃利琴; 韦庆敏

    2012-01-01

    采用机械共混及模压成型工艺将Al2O3粉体,含H20哑铃状液晶化合物(HLCP)与环氧树脂(E-51)共混制备了HLCP/EP/Al2O3复合材料。研究了Al2O3含量对材料热稳定性、导电性能、导热性能及热膨胀的影响。结果表明:材料的导热系数、介电常数及热稳定性随Al2O3含量的增加而增大,当Al2O3粉体质量分数达到70%时,材料导热系数是纯环氧树脂的1.7倍;介电损耗、线膨胀系数随Al2O3含量的增加而减小,当Al2O3粉体质量分数为60%时,介电常数为3.71。同时,由于HLCP网格的存在,降低了材料的内耗,提高了复合材料的玻璃化转变温度,增强了电性能。%The EP/HCLP/Al2O3 composites were prepared by mchanical mixing and compression molding of Al2O3 powder,dumbbell-shaped liquid crystal compounds containing H20(HLCP) and epoxy resin(E-51).The effect of Al2O3 content on the thermal stability,electric properties,heat conducting property and thermal expansion of the composites were studied.The results showed that the thermal conductivity,dielectric constant and thermal stability were increased with the increasing of Al2O3 content.The thermal conductivity of the material with Al2O3 powder mass fraction of 70% was 1.7 times than that of pure epoxy resin.The dielectric loss and linear expansion coefficient were decreased with the increasing of Al2O3 content.The dielectric constant of the composite with Al2O3 powder mass fraction of 60% was 3.71.The same time,due to the existence of liquid crystal compound(HLCP) grid,the internal friction of the material was reduced.The composite glass transition temperature was improved and electrical properties were enhanced.

  10. Compatibility and mechanical properties of liquid crystalline modified aramid reinforced epoxy resin%液晶改性芳纶增强环氧树脂的相容性与力学性能

    Institute of Scientific and Technical Information of China (English)

    张爱玲; 刘慧; 吕震乾; 王松; 李三喜

    2012-01-01

    针对环氧树脂复合材料存在的应力开裂以及与基体界面相容性差等问题,采用液晶和离子单体对芳纶纤维进行改性,再与环氧树脂及固化剂按一定比例混合,制得液晶改性芳纶增强环氧树脂复合材料.正交试验结果表明,常温下固化20 min,芳纶、环氧树脂与固化剂的质量比为0.07∶35∶11,复合材料的弯曲应力为445.6 MPa,应变为0.975%,比水解芳纶增强环氧树脂复合材料、芳纶增强环氧树脂复合材料的弯曲应力分别提高了29%和33%.扫描电镜研究表明,复合材料中分散相在基体中的分散性较好,有良好的界面相容性,断面处的断裂方式由脆性断裂变为韧性断裂.红外光谱研究表明,加入液晶改性芳纶的复合材料出现了磺酸基团和氮氮双键的特征吸收峰.%To solve such problems as stress crack and poor interface compatibility in epoxy resin composites,a liquid crystalline modified aramid reinforced epoxy resin composite was prepared through modifying aramid fiber by liquid crystalline and ion monomer and then mixing with epoxy resin and curing agent in certain proportion.The results of orthogonal experiment reveal that when the mass ratio of aramid fiber,epoxy resin and curing agent is 0.07∶ 35∶ 11 as well as the curing time at room temperature is 20 minutes,the bending stress and strain of the fabricated composite are 445.6 MPa and 0.975%,respectively.The bending stress of liquid crystalline modified aramid reinforced epoxy resin composite increases by 29% and 33% than that of hydrolytic aramid reinforced epoxy resin composite and raw aramid reinforced epoxy resin composite,respectively.The scanning electron microscope observation shows that the modified aramid has good dispersion and interface compatibility in epoxy resin matrix.The fracture mode for the composite changes from brittle fracture to ductile fracture.The infrared spectroscopy(IR) investigation indicates that the S=O and N

  11. 液晶环氧/二元胺/CYD-128体系固化行为的研究%Study on Curing Behavior of Liquid Crystalline Epoxy/Diamine/CYD/128 I Selected Curing Agent and Curing Technology

    Institute of Scientific and Technical Information of China (English)

    陈立新; 王汝敏; 蓝立文

    2001-01-01

    采用含芳香酯类液晶基元的环氧化物(PHBHQ)增韧环氧CYD-128,依据DTA、二元胺的结构、熔点、FTIR分析确定了混胺的比例及固化工艺。通过CYD-128/混胺体系筛选出了较佳的配方,即当n(DDE)∶n(DDS)∶n(DDM)=1∶2.5∶5时,综合性能较佳。%The proportion of mixed amine and curing technology of liquid crystalline epoxy/mixed amine/CYD-128/mixed amine/cy/CYD-128 were determined by DTA,diamice structure,melt point and FTIR.When n(DDE):n(DDS):n(DDM)=1:2.5:5,the coprehensive properties of CYD-128/mixed amine is the best.

  12. The In Vitro Lipolysis of Lipid-Based Drug Delivery Systems: A Newly Identified Relationship between Drug Release and Liquid Crystalline Phase

    OpenAIRE

    Xiao, Lu; Yi, Tao; Liu, Ying; Zhou, Hua

    2016-01-01

    The purpose of this study was to offer a new insight into the microstructure changes during in vitro lipolysis of five lipid-based drug delivery formulations belonging to different lipid formulation types. Five lipid-based formulations of indomethacin were investigated using an in vitro lipolysis model. During lipolysis, microstructures of the intermediate phase formed by lipolytic products were observed. The results showed that the time of liquid crystal formation during in vitro digestion f...

  13. Crystalline and Crystalline International Disposal Activities

    Energy Technology Data Exchange (ETDEWEB)

    Viswanathan, Hari S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Chu, Shaoping [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Reimus, Paul William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Makedonska, Nataliia [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hyman, Jeffrey De' Haven [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Karra, Satish [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dittrich, Timothy M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-12-21

    This report presents the results of work conducted between September 2014 and July 2015 at Los Alamos National Laboratory in the crystalline disposal and crystalline international disposal work packages of the Used Fuel Disposition Campaign (UFDC) for DOE-NE’s Fuel Cycle Research and Development program.

  14. AFM study of advanced composite materials for organic photovoltaic cells with active layer based on P3HT:PCBM and chiral photosensitive liquid crystalline dopants

    Czech Academy of Sciences Publication Activity Database

    Iwan, A.; Sikora, A.; Hamplová, Věra; Bubnov, Alexej

    2015-01-01

    Roč. 42, č. 7 (2015), s. 964-972. ISSN 0267-8292 R&D Projects: GA MŠk 7AMB13PL041; GA ČR GA13-14133S; GA MŠk(CZ) LD14007; GA MŠk 7AMB13PL038 Grant ostatní: AVČR(CZ) M100101204 Institutional support: RVO:68378271 Keywords : AFM * chiral liquid crystal * organic solar cells * azo compounds * photovoltaics Subject RIV: JJ - Other Materials Impact factor: 2.486, year: 2014

  15. Glycation precedes lens crystallin aggregation

    International Nuclear Information System (INIS)

    Non-enzymatic glycosylation (glycation) seems to have the potential to alter the structure of crystallins and make them susceptible to thiol oxidation leading to disulfide-linked high molecular weight (HMW) aggregate formation. They used streptozotocin diabetic rats during precataract and cataract stages and long-term cell-free glycation of bovine lens crystallins to study the relationship between glycation and lens crystallin aggregation. HMW aggregates and other protein components of the water-soluble (WS) and urea-soluble (US) fractions were separated by molecular sieve high performance liquid chromatography. Glycation was estimated by both [3H]NaBH4 reduction and phenylboronate agarose affinity chromatography. Levels of total glycated protein (GP) in the US fractions were about 2-fold higher than in the WS fractions and there was a linear increase in GP in both WS and US fractions. This increase was parallelled by a corresponding increase in HMW aggregates. Total GP extracted by the affinity method from the US fraction showed a predominance of HMW aggregates and vice versa. Cell-free glycation studies with bovine crystallins confirmed the results of the animals studies. Increasing glycation caused a corresponding increase in protein insolubilization and the insoluble fraction thus formed also contained more glycated protein. It appears that lens protein glycation, HMW aggregate formation, and protein insolubilization are interrelated

  16. 苄醚型树枝化碳水化合物的合成与液晶性%Benzyl ether type of dendronized carbohydrates:Synthesis and liquid crystallinity

    Institute of Scientific and Technical Information of China (English)

    杨柳林; 曹擎; 董炎明; 胡晓兰; 刘安华; 赵雅青

    2012-01-01

    Most of traditional carbohydrate liquid crystals are composed of sugar moiety substituted by n-alkyl chains. There are still quite limited categories in this liquid crystal library. In this study, dendronized carbohydrate liquid crystals were synthesized with N-acetylglucosamine as core unit, and wedge or taper shaped benzyl ether type dendrons as branches. Liquid crystallinity of dendronized carbohydrates was studied by POM, DSC, XRD, CD/UV spectroscopy. Molecules contain wedge shaped dendrons can self-organize into chiral columnar hexagonal phase or achiral nematic phase, while molecules contain taper shaped dendrons still self-organize into chiral columnar hexagonal phase, not however cubic phase as suspected. Supramolecular chirality is most probably derived from a helical arrangement of dendrimers around the cylinder axis, driven by a collaborative self-assembly of carbohydrate core and dendron branches, and the chiral carbohydrate center plays the primary role of selecting the handedness of the helix so as not to be racemization. This novel dendronized carbohydrate liquid crystal may provide inspiration in the study of chiral supramolecular aggregates induced by carbohydrates.%选取3种不同结构的苄醚型树枝状分子为分枝,以N-乙酰氨基葡萄糖为内核,合成出一类树枝化碳水化物;利用DSC、热台偏光显微镜、XRD和CD/UV光谱等手段研究该类化合物的液晶性,并命名为树状碳水化合物液晶.研究表明,连接有楔形树枝状单元的化合物形成手性柱状六方相或者向列相,连接有锥形树枝状单元的化合物未能如预期形成立方相,而仍然形成手性柱状六方相.超分子手性很可能源于树枝状单元与糖内核的协同自组装,使得树状分子沿着柱轴螺旋式堆砌;而糖环内核则对超分子柱的手性起调控作用,从而避免了外消旋的发生.该类化合物为研究碳水化合物诱导手性超分子聚集体提供了新的思路.

  17. Crystalline mesophases: Structure, mobility, and pharmaceutical properties.

    Science.gov (United States)

    Shalaev, Evgenyi; Wu, Ke; Shamblin, Sheri; Krzyzaniak, Joseph F; Descamps, Marc

    2016-05-01

    Crystalline mesophases, which are commonly classified according to their translational, orientational, and conformational order as liquid crystals, plastic crystals, and conformationally disordered crystals, represent a common state of condensed matter. As an intermediate state between crystalline and amorphous materials, crystalline mesophases resemble amorphous materials in relation to their molecular mobility, with the glass transition being their common property, and at the same time possessing a certain degree of translational periodicity (with the exception of nematic phase), with corresponding narrow peaks in X-ray diffraction patterns. For example, plastic crystals, which can be formed both by near-spherical molecules and molecules of lower symmetry, such as planar or chain molecules, can have both extremely sharp X-ray diffraction lines and exhibit glass transition. Fundamentals of structural arrangements in mesophases are compared with several types of disorder in crystalline materials, as well as with short-range ordering in amorphous solids. Main features of the molecular mobility in crystalline mesophases are found to be generally similar to amorphous materials, although some important differences do exist, depending on a particular type of mobility modes involved in relaxation processes. In several case studies reviewed, chemical stability appears to follow the extent of disorder, with the stability of crystalline mesophase found to be intermediate between amorphous (least stable) and crystalline (most stable) materials. Finally, detection of crystalline mesophases during manufacturing of two different types of dosage forms is discussed. PMID:27067607

  18. Synthesis and Liquid Crystalline Properties of a Chiral Monomer and Polymer Containing Menthyl Group%一种含薄荷基的手性单体及其聚合物的合成与液晶性能

    Institute of Scientific and Technical Information of China (English)

    徐孝旭

    2011-01-01

    制备了一种含薄荷基的手性单体及其对应的液晶聚合物,其化学结构、纯度及旋光性质采用红外光谱(FT-IR)、核磁共振(1H-NMR)及旋光仪进行表征,采用差示扫描量热(DSC)与偏光显微镜(POM)等研究了单体与聚合物的介晶性能和相行为,并用热重分析(TGA)表征了聚合物的热稳定性。结果表明,手性单体呈现胆甾相的油丝织构与焦锥织构,且出现了明显的选择反射现象,主要反射颜色为红色与绿色,且随温度的升高,反射波长发生"蓝移",而聚合物则呈现胆甾相的Grandjean织构。此外,TGA表明液晶聚合物具有良好的热稳定性,热分解温度为335℃。%A chiral liquid crystalline monomer and their corrresponding polymer containing menthyl groups were synthesized.The chemical structures were characterized with FT-IR,1H-NMR,and specific optical rotation was evaluated with a polarimeter.The liquid crystalline properties and phase behavior were investigated by differential scanning calorimetry(DSC) and polarizing optical microscopy(POM).The thermal stability of the polymer was studied with thermogravimetric analysis(TGA).The chiral monomer shows the oily streak texture and the focal conic texture of the cholesteric phase,the selective reflection color is mainly red and green,the selective reflection of light shifted to the short wavelength region.The polymer shows cholesteric grandjean texture.In addition,TGA result shows that the obtained polymer has a good stability,and the temperature at which 5 % weight loss occurred(Td) is 335 ℃.

  19. 剪切扰动对液晶聚合物流变行为影响的数值模拟%Numerical simulation of effect of shear perturbations on theology behavior of liquid crystalline polymers

    Institute of Scientific and Technical Information of China (English)

    苏进; 欧阳洁; 王晓东

    2011-01-01

    The complex rheological behavior of liquid crystalline polymers solutions in the shear flow with perturbations is investigated using the finite volume method. The perturbations of simple shear can be considered as one arising from the addition of a slight extensional component to the velocity gradient. Firstly, the case in the simple shear flow is focused upon, i.e. , the perturbation equal to zero,and some classical solutions can be obtained for various parameter values. This is the preparation for the discussion of perturbation cases, and to check the validity of numerical method. Then, the effect of slight perturbations on the transition to the flow type of liquid-crystalline polymers (LCPs) is explored in detail. Results indicate that the mechanism of transformation is different for low and high shear rates. Finally, rheological predictions and some micro properties of orientation are also obtained from the perturbation system, and the results show that the effect of perturbations in flow type can also significantly change the related material functions.%采用有限体积数值方法模拟了剪切扰动条件下液晶聚合物的复杂流变性特性.其中剪切扰动系统通过给速度梯度施加一项额外小量而实现.首先,考虑了扰动为零的简单剪切流情形,分别得到了各种典型的分子运动状态,不但为剪切扰动的定性分析作了准备,而且也验证了数值算法的有效性.然后,重点研究了剪切扰动对分子运动行为转变的影响,数值结果表明流场中微小的剪切扰动在低剪切率和高剪切率下对分子演化状态的转变机理并不相同.此外,进一步预测了液晶聚合物流变行为及微观特性的变化,结果发现流场的扰动作用也会显著地改变其相应的物性函数.

  20. On some liquid crystalline phases exhibited by compounds made of bent-core molecules and their mixtures with rod-like molecules

    Indian Academy of Sciences (India)

    R Pratibha; N V Madhusudana; B K Sadashiva

    2003-08-01

    In most homologous series of compounds made of bent-core (BC) molecules, the B2, B1 and B6 phases occur as the chain length decreases. We have studied binary mixtures of the compound 1,3-phenylene bis[4-(3-methylbenzoyloxy)]4'--dodecylbiphenyl 4'-carboxylate (BC12) which exhibits the B2 phase with the compound 4-biphenylyl 4''--undecyloxybenzoate (BO11) made of rod-like (R) molecules. We find the above sequence of occurrence of the B phases with increasing concentration of BO11. In this paper we describe the physical origin for the formation of these phases in both pure compounds and in the mixtures. We have also found the occurrence of the biaxial smectic A phase when the BO11 concentration is increased to 87–95.5 mol%. We also report on another binary system composed of BC12 and 4--octyloxy 4'- cyanobiphenyl (8OCB) made of R molecules. This system exhibits the biaxial smectic A phase down to 30°C. Using polarized infrared spectroscopy we find that the mutual orientation of the R and BC molecules in the SmAdb liquid crystal is such that the arrow axes of the BC molecules are along the layer normal of the partial bilayer smectic structure formed by the rods. We also describe unusual growth patterns obtained when the nematic phase transforms to the SmAdb phase in a mixture with 24 mol% of BC12.

  1. Investigation of Solute-Fiber Affinity and Orientational Ordering of Norbornadiene Interacting with Two-Polypeptide Chiral Liquid Crystalline Solvents by Natural Abundance Deuterium (NAD) NMR.

    Science.gov (United States)

    Serhan, Zeinab; Aroulanda, Christie; Lesot, Philippe

    2016-08-01

    A prochiral bridged compound of C2v symmetry, the norbornadiene (NBD), oriented in a chiral liquid crystal composed of various mixtures of poly-γ-benzyl-l-glutamate (PBLG) and poly-ε-carboxy-l-lysine (PCBLL), two chiral homopolypeptides, is investigated using natural abundance deuterium 2D-NMR (NAD 2D-NMR) spectroscopy. In such chiral oriented solvents, enantiotopic directions are spectrally nonequivalent, and two distinct (2)H quadrupolar doublets associated with enantioisotopomeric pairs of NBD are detected. As the two homopolypeptides have the same absolute configuration but distinct chemical functions in their side chains, the variation of residual quadrupolar couplings (RQC's) allows the determination of the relative solute-fiber affinities toward the two polypeptides in these lyotropic bipolymeric systems. Besides the experimental measurement of RQC's and the determination of their signs at each inequivalent (2)H site, the elements of the second-rank order tensor, Sαβ, are calculated by assuming a modeled structure. The variations of RQC's and diagonalized order parameters, Sα'α', are followed versus the relative proportion of two polypeptides in the chiral oriented mixture. The influence of the solute mass fraction in the two-homopolypeptide oriented samples is also examined as well as the case of homogeneous and uniform achiral mesophases "PBG-PCBL" made of two pairs of mirror-image homopolypeptides (PBLG/PBDG and PCBLL/PCBDL). In the latter, the solute ordering is modulated by the proportion of each type of homopolypeptide (chemical nature and absolute configuration), leading to eliminate the enantiodiscrimination mechanisms on the average. In the frame of a model, new insights on the solute-homopolypeptide fiber interactions are discussed. PMID:27383731

  2. Crystalline Silica Primer

    Science.gov (United States)

    Staff- Branch of Industrial Minerals

    1992-01-01

    Crystalline silica is the scientific name for a group of minerals composed of silicon and oxygen. The term crystalline refers to the fact that the oxygen and silicon atoms are arranged in a threedimensional repeating pattern. This group of minerals has shaped human history since the beginning of civilization. From the sand used for making glass to the piezoelectric quartz crystals used in advanced communication systems, crystalline silica has been a part of our technological development. Crystalline silica's pervasiveness in our technology is matched only by its abundance in nature. It's found in samples from every geologic era and from every location around the globe. Scientists have known for decades that prolonged and excessive exposure to crystalline silica dust in mining environments can cause silicosis, a noncancerous lung disease. During the 1980's, studies were conducted that suggested that crystalline silica also was a carcinogen. As a result of these findings, crystalline silica has been regulated under the Occupational Safety and Health Administration's (OSHA) Hazard Communication Standard (HCS). Under HCS, OSHAregulated businesses that use materials containing 0.1% or more crystalline silica must follow Federal guidelines concerning hazard communication and worker training. Although the HCS does not require that samples be analyzed for crystalline silica, mineral suppliers or OSHAregulated

  3. Axial-bundle phases--new modes of 2D, 3D, and helical columnar self-assembly in liquid crystalline phases of bolaamphiphiles with swallow tail lateral chains.

    Science.gov (United States)

    Prehm, Marko; Liu, Feng; Zeng, Xiangbing; Ungar, Goran; Tschierske, Carsten

    2011-04-01

    Two series of polyphilic molecules composed of a rigid and linear p-terphenyl core, terminated at both ends with polar glycerol groups capable of hydrogen bonding, and two branched swallow tail-type lateral chains, composed of a fluorinated and a nonfluorinated branch or two fluorinated branches, were synthesized and investigated by differential scanning calorimetry, polarizing microscopy, and X-ray diffraction (XRD) with respect to their self-assembly in thermotropic liquid crystalline (LC) phases. Hexagonal columnar phases were formed by all molecules, at least at the highest temperature. In these phases the columns are composed of a core of aromatic rods and an aliphatic shell. The aromatic rods form bundles which are rotationally averaged and lie parallel to the column long axis. This unique organization is proven by different optical and XRD methods. The aromatic and glycerol groups inside the rod bundles are segregated into alternating segments. Depending on temperature and molecular structure, long-range intercolumnar correlation of this periodicity could take place, leading to a 3D-ordered LC phase with rhombohedral R ̄3m symmetry. The bundles are embedded in the matrix of the lateral chains, which is divided into fluoroalkyl- and aliphatic-rich regions. In the 2D columnar phase the fluorinated regions take the form of either straight columns running along the edges of the hexagonal Voronoi cells or, for compounds with a higher degree of fluorination, fuse to a hexagonal honeycomb enclosing the aromatic cores. In the R ̄3m phase the fluorine-rich chains are preferentially found along right- and left-handed helices wound around the 3(1) screw axes between the main aromatic columns. PMID:21391683

  4. The Preparation and Heat-Treatment of Thermotropic Liquid-Crystalline Polyarylate Fiber%热致性液晶聚芳酯纤维的制备与热处理

    Institute of Scientific and Technical Information of China (English)

    甘海啸; 朱卫彪; 王燕萍; 王依民

    2011-01-01

    热致性液晶聚芳酯(TLCP)纤维是一类具有较高强度与模量的高性能纤维.将由4,4-二苯醚二甲酸、4-乙酰氧基苯甲酸、1,4-二乙酰氧基苯撑、2,6-萘二甲酸和对苯二甲酸熔融缩聚制得的新型液晶聚芳酯,通过熔融纺丝制得初生纤维,然后经热处理,制备高强、高模TLCP纤维.通过金相显微镜、差示扫描量热仪、热失重仪、纤维强力仪等对该TLCP初生纤维与热处理后的纤维性能进行了研究和表征.%The thermotropic liquid-crystalline polyarylate fiber has aroused wide public concern attributable to not only to it's high modulus and high strength, but also it's good heat resistance, chemical resistance,inherent flame retardancy, low creep and good for processing behavior. In this study, a new TLCP melt polymerized with 4,4'-diphenyloxide dicarboxylie acid (DODA), 4-aeetoxybenzoic acid (ABA), hydroquinone diaetate (HQA), 2,6-naphthalene dicarboxylie (NDA) and terephthalic acid (TA), then melt spun into TLCP fibers, and TLCP fibers were heat treated to enhance the breaking strength and Young's modulus. The thermal properties of the TLCP fibers were investigated by employing differential scanning calorimetry (DSC) and TGA, the structure of the fiber was investigated by optical microscope, and the mechanical properties were tested by the fiber tensile tester.

  5. Effect of expanded graphite and PEI-co-Silicon Rubber on the thermo mechanical, morphological as well as rheological properties of in situ composites based on poly (ether imide) and liquid crystalline polymer

    International Nuclear Information System (INIS)

    Highlights: • PEI/LCP/ PEI-co-Silicon Rubber/EG and PEI/LCP/MWCNT nano composites are prepared by melt blending method. • The dispersions of acid modified expanded graphite were improved in presence of PEI-co-Silicon Rubber. • Thermal stability was found to be highest for PLGC composite. • Storage modulus and Young’s modulus showed an upward trend with incorporation of only EG and EG in presence of PEI-co-Silicon Rubber. • Among the nano composites PLGC has highest viscosity. - Abstract: Nanocomposites of polyether imide (PEI) and liquid crystalline polymer (LCP) with either MWCNT, Expanded Graphite (EG) or in combination of both EG and PEI-co-Silicon Rubber were prepared by melt blending process. The compatibility between the polymeric phases (PEI and LCP) was observed to be increased by the addition of PEI-co-Silicon Rubber while the only MWCNT added system (PLC) resulted in smaller LCP droplets. A continuous morphology was produced in presence of both PEI-co-Silicon Rubber and EG both added system (PLGR). This was due to the compatibilizing effect of PEI-co-Silicon Rubber. FTIR analysis revealed interaction between PEI and LCP in presence of PEI-co-Silicon Rubber. Remarkable increment of storage modulus was observed with the addition of EG and PEI-co-Silicon Rubber. Transmission Electron Microscope (TEM) analysis showed better dispersion of multiple graphene layers of EG in presence of PEI-co-Silicon Rubber compatibilized system. Tensile and Young’s modulus both were highest for EG/ PEI-co-Silicon Rubber added system. This is due to flexible compatibilizing effect of PEI-co-Silicon Rubber which delayed the detachment of LCP domain from the PEI matrix and thus detains the fracture

  6. Liquid crystalline critical dynamics in decylammonium chloride

    CERN Document Server

    Lee, K W; Lee, C E; Kang, K H; Rhee, C; Kang, J K

    1999-01-01

    Collective chain dynamics and phase transitions in a model biomembrane, decylammonium chloride (C sub 1 sub 0 H sub 2 sub 1 NH sub 3 Cl), were studied by means of proton nuclear magnetic resonance. Our measurements sensitively reflect the critical dynamics associated with the smectic C to smectic A transition of the lipid bilayer.

  7. Liquid crystalline critical dynamics in decylammonium chloride

    International Nuclear Information System (INIS)

    Collective chain dynamics and phase transitions in a model biomembrane, decylammonium chloride (C10H21NH3Cl), were studied by means of proton nuclear magnetic resonance. Our measurements sensitively reflect the critical dynamics associated with the smectic C to smectic A transition of the lipid bilayer

  8. Liquid crystalline networks for electroluminescent displays

    International Nuclear Information System (INIS)

    This work presents the first low molar mass organic electroluminescent (EL) material to form a nematic glass and then emit plane-polarised light from the vitrified state on application of an electric field. Photocrosslinkable molecules are also discussed which form insoluble films on illumination with ultra-violet light. This approach combines the ease of deposition of small molecules with the robustness and stability of polymers, allowing simple fabrication of multi-layer EL devices and photo-patterning. A range of conjugated low molar-mass molecules are considered, containing the anthracene, perylene and fluorene cores, with the aims of producing a general recipe for efficient EL, based on ordered, stable nematics at room temperature. Many physical properties are compared and molecular mechanics modeling is used to represent molecular geometries. An acrylate and several diene photo-polymerisable derivatives of the fluorenes undergo photo-crosslinking. Infrared and photoluminescence spectroscopy is used to examine crosslinking in detail and to optimise exposure conditions. The diene shows no significant degradation for an optimal exposure, but requires a high fluence of 100 Jcm-2 to form an insoluble film. A doped photo-alignment layer is used for the first time to obtain polarised El with ratio 11:1 and 80 cdm-2 brightness from the crosslinked diene. The insoluble crosslinked network allows spin coating of an electron transporting over-layer, resulting in increased brightness. Complex impedance spectroscopy and time of flight measurements confirm good material properties with complete depletion of the crosslinkable diene molecule and non-dispersive conduction. Finally, a novel deposition technique, pulsed laser deposition (PLD), is presented, as an alternative to spin coating or vapour deposition. Minimal degradation is observed for optimised deposition conditions and a PLD film is successfully demonstrated in an EL device. (author)

  9. Liquid crystalline networks for electroluminescent displays

    CERN Document Server

    Contoret, A E A

    2001-01-01

    This work presents the first low molar mass organic electroluminescent (EL) material to form a nematic glass and then emit plane-polarised light from the vitrified state on application of an electric field. Photocrosslinkable molecules are also discussed which form insoluble films on illumination with ultra-violet light. This approach combines the ease of deposition of small molecules with the robustness and stability of polymers, allowing simple fabrication of multi-layer EL devices and photo-patterning. A range of conjugated low molar-mass molecules are considered, containing the anthracene, perylene and fluorene cores, with the aims of producing a general recipe for efficient EL, based on ordered, stable nematics at room temperature. Many physical properties are compared and molecular mechanics modeling is used to represent molecular geometries. An acrylate and several diene photo-polymerisable derivatives of the fluorenes undergo photo-crosslinking. Infrared and photoluminescence spectroscopy is used to e...

  10. Liquid Crystalline Polymers for Smart Applications

    OpenAIRE

    Artur Bogdanowicz, Krzysztof

    2015-01-01

    Polímers cristall-líquids (PCL) posseeixen propietats que són una combinació entre sòlids cristal·lins i fluids. Actualment, PCL que incorporen elements actius en l'estructura (pe, grups de foto-sensibles, dendrons, etc.) condueixen a un material selectivament sensible. S'informa que els polímers es poden aplicar en diversos sistemes pe com materials amb memòria de forma, sensors o pantalles foto-òptiques. Els nostres estudis se centren en dues aplicacions diferents: microcàpsules fotosensibl...

  11. What Is Crystalline Silica?

    Science.gov (United States)

    ... 1926.55, 1910.1000). OSHA also requires hazard communication training for workers exposed to crystalline silica, and ... identify, reduce, and eliminate health hazards associated with occupational ... safety and health? OSHA has various publications, standards, technical ...

  12. 热致液晶PET-PHB共聚酯增韧改性环氧树脂%Toughening Epoxy Resins by Liquid Crystalline Co-Polyester PET-PHB

    Institute of Scientific and Technical Information of China (English)

    曹有名; 石胜伟; 孙军; 于德梅

    2001-01-01

    The toughness of the epoxy resins is modified by liquid crystalline copolyester PET-PHB.The morphologies of the fracture surface were observed by scanning electron microscope (SEM).The relationships between the morphologies and mechanical properties were discussed. The results revealed that the moduli, tensile and impact strengths of the modified epoxy resins are much higher than those of the unmodified epoxy resin. The maximum values have been reached in the tensile and impact strength of the modified epoxy resins by adding PET-PHB copolyester of 10%.At the same time,an uniformly network microstructure emerged on the fracture surface of the toughened epoxy resins, which is obviously different from that of the unmodified epoxy resin. It is believed that the formation of the uniformly network microstructure resulted in the significant improvement of impact and tensile strength of the epoxy resins.%采用熔融共混方法,用热致液晶PET-PHB共聚酯对环氧树脂进行增韧改性,并研究了共混体系的力学性能.借助扫描电镜,对材料断裂面的形态结构进行了分析,探讨了体系的形态结构与冲击性能之间的关系.研究结果表明,改性材料的弹性模量高于纯环氧树脂,其冲击强度及拉伸强度均有大幅度提高.当PET-PHB共聚酯的加入量为10%时,环氧改性材料的拉伸强度及冲击强度均为最大值.此时,改性材料的断面形态呈微观网络分布,明显不同于未改性环氧树脂脆性断裂的台阶型结构.

  13. Study on epoxy/liquid crystalline epoxy/montmorillonite nanocomposites%环氧树脂/环氧液晶/蒙脱土纳米复合材料研究

    Institute of Scientific and Technical Information of China (English)

    徐旭; 陆绍荣; 余传柏

    2013-01-01

    采用液晶环氧预聚物(PHQEP)与有机蒙脱土(OMMT)共混改性环氧树脂制备三元共混体系的环氧基复合材料.用X射线衍射法(XRD)测试了有机化蒙脱土在被插层前后片层间距的变化,通过DSC、TGA及SEM等对PHQEP/OMMT增韧改性环氧树脂固化体系的力学性能,热性能及微观相态结构进行了研究.结果表明:当PHQEP质量分数为5%,添加1.5%的有机蒙脱土可以使环氧树脂的冲击强度达到最大值23.43 kJ/m2,比纯环氧树脂提高2倍左右,玻璃化转变温度及5%热分解温度比纯环氧树脂分别高出15℃和27℃.PHQEP与OMMT的加入使纳米复合材料的力学性能和热性能得到明显提高.%The epoxy matrix composites of ternary blends were prepared from liquid crystalline epoxy prepolymer (PHQEP) and organic montmorillonite (OMMT) blending modification of epoxy resin. The changes of lamellar spacing of organic montmorillonite beore and after intercalation were tested by X -ray diffraction (XRD). The mechanical properties , thermal performance and morphology of PHQEP/OMMT toughening modified epoxy resin curing system were investigated by DSC, TGA and SEM. The results showed that the impact strength of the epoxy resin was a-chieved the maximum 23.43 kJ/m2 and increased by about two times than that of pure epoxy resin, when mass fraction of PHQEP was 5% and organic montmorillonite was 1. 5% . The glass transition temperature and 5% thermal decomposition temperature were increased by 15 ℃ and 27 ℃, respectively than that of pure epoxy resin. The mechanical and thermal performance of nanocomposites were improved significantly by adding PHQEP and OMMT.

  14. Strong Acid-Nonionic Surfactant Lyotropic Liquid-Crystalline Mesophases as Media for the Synthesis of Carbon Quantum Dots and Highly Proton Conducting Mesostructured Silica Thin Films and Monoliths.

    Science.gov (United States)

    Olutaş, Elif B; Balcı, Fadime M; Dag, Ömer

    2015-09-22

    Lyotropic liquid-crystalline (LLC) materials are important in designing porous materials, and acids are as important in chemical synthesis. Combining these two important concepts will be highly beneficial to chemistry and material science. In this work, we show that a strong acid can be used as a solvent for the assembly of nonionic surfactants into various mesophases. Sulfuric acid (SA), 10-lauryl ether (C12E10), and a small amount of water form bicontinuous cubic (V1), 2D-hexagonal (H1), and micelle cubic (I1) mesophases with increasing SA/C12E10 mole ratio. A mixture of SA and C12E10 is fluidic but transforms to a highly ordered LLC mesophase by absorbing ambient water. The LLC mesophase displays high proton conductivity (1.5 to 19.0 mS/cm at room temperature) that increases with an increasing SA content up to 11 SA/C12E10 mole ratio, where the absorbed water is constant with respect to the SA amount but gradually increases from a 2.3 to 4.3 H2O/C12E10 mole ratio with increasing SA/C12E10 from 2 to 11, respectively. The mixture of SA and C12E10 slowly undergoes carbonization to produce carbon quantum dots (c-dots). The carbonization process can be controlled by simply controlling the water content of the media, and it can be almost halted by leaving the samples under ambient conditions, where the mixture slowly absorbs water to form photoluminescent c-dot-embedded mesophases. Over time the c-dots grow in size and increase in number, and the photoluminescence frequency gradually shifts to a lower frequency. The SA/C12E10 mesophase can also be used as a template to produce highly proton conducting mesostructured silica films and monoliths, as high as 19.3 mS/cm under ambient conditions. Aging the silica samples enhances the conductivity that can be even larger than for the LLC mesophase with the same amount of SA. The presence of silica has a positive effect on the proton conductivity of SA/C12E10 systems. PMID:26332603

  15. Synthesis and application of liquid crystalline polyurethanes/epoxy resin composites%液晶聚氨酯/环氧树脂复合材料的合成及应用

    Institute of Scientific and Technical Information of China (English)

    黄志义; 陆绍荣; 阳志有; 于春贺; 郭栋

    2011-01-01

    Liquid crystal polyurethans(HBLCP) containing imide units were synthesized by polyaddition reaction of N,N'-bis(2-hydroxyhexyl)-dicarboxyimide(BHDI) with 2,4-toluenediisocyanate(2,4-TDI) and hydroquinone dibenzoate ester(HQB) through changing the molar ratio of BHDI and HQB,and blending HBLCP with epoxy resin(E-51),to prepare HBLCP/E-51 composites.The structure and liquid crystalline phase behavior of HBLCP were characteristied by using FTIR,DSC,polarized light microscopy(POM),X-ray diffraction(WAXD),and the fracture structure of the HBLCP/E-51 composites was investigated by SEM,and the toughening mechanism was also explored.Experimental results reveale that the impact strength of the epoxy resin modified with 3 wt% HBLCP is 2.3 times higher than that of unmodified epoxy resin,and the tensile strength as well as the bending strength is also improved,present the typical ductile fracture.The thermal decomposition temperature of HBLCP/E-51 composites is also 12~20 ℃ higher than that of the pure epoxy resin,and the temperature for the maximum decomposition rate of composites is 12~15 ℃ higher than that of the pure epoxy resin.%以对苯二酚二对苯甲酸酯(HQB)、N,N’-二(ω-羟乙基)苯均四甲酰二亚胺(BHDI)、甲苯二异氰酸酯(TDI)为单体,利用溶液缩聚方法,合成了一种含有亚氨基的新型液晶聚氨酯(HBLCP),并将该液晶聚氨酯与环氧树脂(E-51)共混制备液晶聚氨酯/环氧树脂复合材料(HBLCP/E-51)。采用FTIR、DSC、POM和WAXD等方法对HBLCP的结构和液晶相转变行为进行了表征,并利用SEM观察复合材料断裂形貌,探讨其增韧机制。结果表明,加入质量分数为3%的HBLCP,可使HBLCP/E-51复合材料的冲击强度提高2.3倍,拉伸强度和弯曲强度也有不同程度的提高,呈现出典型的韧性断裂,热分解温度提高12~20℃,出现最大分解速率时的温度提高12~15℃。

  16. Fractured unconventional reservoirs in the Crystalline Basement

    Science.gov (United States)

    Plotnikova, Irina

    2015-04-01

    Since the late 1960-es, the crystalline basement of Tatarstan has been in the focus of intense geological and geophysical surveys. Since 1975, within the framework of the Subsoil Survey Program of Tatarstan, two extra deep wells have been drilled in the Republic, including: 20000-Minnibaevskaya well (bottomhole depth - 5,099 m, meters drilled in the basement - 3,215 m) and 20009-Novoelkhovskaya well (bottomhole depth - 5,881 m, meters drilled in the basement - 4,077 m), as well as 24 wells penetrating the basement at depth from 100 to 2,432 m. Reservoir properties of the crystalline basement rocks can be evaluated based on the resulting volumes of produced liquid, which vary from 0.027 to 125 m3/day. The highest flow rate was registered for well № 20000 Minnibaevskaya. Therefore, there are high-capacity reservoir zones in the crystalline basement of the eastern margin of the Russian Platform. The statement saying that natural reservoirs with significant sizes and fluid storage capacities occur everywhere within the Precambrian crystalline massive on the territory of Tatarstan can be justified by the following provisions: - deconsolidation and fracturing zones of the crystalline basement are registered by a full set of geological and geophysical methods applied in the process of geophysical well surveys and in the process of surface geophysical studies; - there is a certain regular pattern of crystalline basement zone distribution by area and by profile. Wide-spaced drilling into the crystalline basement helped to identify numerous zones of deconsolidation and fracturing with different fluid storage capacity and different extent of fluid saturation. Thickness of the crystalline basement reservoir zones varies from several meters to dozens of meters. Such zones were identified close to the crystalline basement top, As well as at depths more than 5 km. Well log survey was the key method used for reservoir differentiation in the crystalline basement. In total, 16

  17. Attenuation of Thermal Neutrons by Crystalline Silicon

    International Nuclear Information System (INIS)

    A simple formula is given which allows to calculate the contribution of the total neutron cross - section including the Bragg scattering from different (hkt) planes to the neutron * transmission through a solid crystalline silicon. The formula takes into account the silicon form of poly or mono crystals and its parameters. A computer program DSIC was developed to provide the required calculations. The calculated values of the total neutron cross-section of perfect silicon crystal at room and liquid nitrogen temperatures were compared with the experimental ones. The obtained agreement shows that the simple formula fits the experimental data with sufficient accuracy .A good agreement was also obtained between the calculated and measured values of polycrystalline silicon in the energy range from 5 eV to 500μ eV. The feasibility study on using a poly-crystalline silicon as a cold neutron filter and mono-crystalline as a thermal neutron one is given. The optimum crystal thickness, mosaic spread, temperature and cutting plane for efficiently transmitting the thermal reactor neutrons, while rejecting both fast neutrons and gamma rays accompanying the thermal ones for the mono crystalline silicon are also given

  18. Polymer Blends Containing Liquid Crystalline Component Cholesteryl Palmitate-containing Blends%含液晶成分的掺杂共聚物和胆甾醇基棕榈酸盐(或酯)掺合物

    Institute of Scientific and Technical Information of China (English)

    Maria-Cristina; Popescu; Cornelia; Vasile; Daniela; Filip; Doina; Macocinschi; Gh.; Singurel

    2005-01-01

    @@ Physical blends containing macromolecular compounds and low molecular weight liquid crystals (LCs) have important applications. LCs are used as reinforcements for amorphous polymers or in display devices.

  19. Thermodynamics of Crystalline States

    CERN Document Server

    Fujimoto, Minoru

    2013-01-01

    Thermodynamics is a well-established discipline of physics for properties of matter in thermal equilibrium with the surroundings. Applying to crystals, however, the laws encounter undefined properties of crystal lattice, which therefore need to be determined for a clear and well-defined description of crystalline states. Thermodynamics of Crystalline States explores the roles played by order variables and dynamic lattices in crystals in a wholly new way. The book begins by clarifying basic concepts for stable crystals. Next, binary phase transitions are discussed to study collective motion of order variables, as described mostly as classical phenomena. New to this edition is the examination of magnetic crystals, where magnetic symmetry is essential for magnetic phase transitions. The multi-electron system is also discussed  theoretically, as a quantum-mechanical example, for superconductivity in metallic crystals. Throughout the book, the role played by the lattice is emphasized and studied in-depth. Thermod...

  20. Colliding Crystalline Beams

    International Nuclear Information System (INIS)

    The understanding of crystalline beams has advanced to the point where one can now, with reasonable confidence, undertake an analysis of the luminosity of colliding crystalline beams. Such a study is reported here. It is necessary to observe the criteria, previously stated, for the creation and stability of crystalline beams. This requires, firstly, the proper design of a lattice. Secondly, a crystal must be formed, and this can usually be done at various densities. Thirdly, the crystals in a colliding-beam machine are brought into collision. We study all of these processes using the molecular dynamics (MD) method. The work parallels what was done previously, but the new part is to study the crystal-crystal interaction in collision. We initially study the zero-temperature situation. If the beam-beam force (or equivalent tune shift) is too large then over-lapping crystals can not be created (rather two spatially separated crystals are formed). However, if the beam-beam force is less than but comparable to that of the space-charge forces between the particles, we find that overlapping crystals can be formed and the beam-beam tune shift can be of the order of unity. Operating at low but non-zero temperature can increase the luminosity by several orders of magnitude over that of a usual collider. The construction of an appropriate lattice, and the development of adequately strong coding, although theoretically achievable, is a challenge in practice

  1. Crystalline beam ground state

    International Nuclear Information System (INIS)

    In order to employ molecular dynamics (MD) methods, commonly used in condensed matter physics, we have derived the equations of motion for a beam of charged particles in the rotating rest frame of the reference particle. We include in the formalism that the particles are confined by the guiding and focusing magnetic fields, and that they are confined in a conducting vacuum pipe while interacting with each other via a Coulomb force. Numerical simulations using MD methods has been performed to obtain the equilibrium crystalline beam structure. The effect of the shearing force, centrifugal force, and azimuthal variation of the focusing strength are investigated. It is found that a constant gradient storage ring can not give a crystalline beam, but that an alternating-gradient (AG) structure can. In such a machine the ground state is, except for one-dimensional (1-D) crystals, time dependent. The ground state is a zero entropy state, despite the time-dependent, periodic variation of the focusing force. The nature of the ground state, similar to that found by Schiffer et al. depends upon the density and the relative focusing strengths in the transverse directions. At low density, the crystal is 1-D. As the density increases, it transforms into various kinds of 2-D and 3-D crystals. If the energy of the beam is higher than the transition energy of the machine, the crystalline structure can not be formed for lack of radial focusing

  2. Some problems of the statistical theory of polymeric lyotropic liquid crystals

    International Nuclear Information System (INIS)

    In this article we consider some topics of the statistical physics of liquid-crystalline phase in the solutions of stiff chain macromolecules. Among these topics are: the problem of the phase diagram for the liquid-crystalline transition in the solutions of completely stiff macromolecules (rigid rods); conditions of formation of the liquid-crystalline phase in the solutions of semiflexible macromolecules; possibility of the intramolecular liquid-crystalline ordering in semiflexible macromolecules; structure of intramolecular liquid crystals and dependence of the properties of the liquid-crystalline phase on the microstructure of the polymer chain. (author)

  3. Flexoelectricity in an oxadiazole bent-core nematic liquid crystal

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, S., E-mail: Sarabjot.Kaur@manchester.ac.uk; Panov, V. P.; Gleeson, H. F. [School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); Greco, C.; Ferrarini, A. [Department of Chemical Sciences, University of Padua, Padua I-35131 (Italy); Görtz, V. [Department of Chemistry, University of York, York YO10 5DD (United Kingdom); Department of Chemistry, University of Lancaster, Lancaster LA1 4YB (United Kingdom); Goodby, J. W. [Department of Chemistry, University of York, York YO10 5DD (United Kingdom)

    2014-12-01

    We have determined experimentally the magnitude of the difference in the splay and bend flexoelectric coefficients, |e{sub 1} − e{sub 3}|, of an oxadiazole bent-core liquid crystal by measuring the critical voltage for the formation of flexodomains together with their wave number. The coefficient |e{sub 1} − e{sub 3}| is found to be a factor of 2–3 times higher than in most conventional calamitic nematic liquid crystals, varying from 8 pCm{sup −1} to 20 pCm{sup −1} across the ∼60 K—wide nematic regime. We have also calculated the individual flexoelectric coefficients e{sub 1} and e{sub 3}, with the dipolar and quadrupolar contributions of the bent-core liquid crystal by combining density functional theory calculations with a molecular field approach and atomistic modelling. Interestingly, the magnitude of the bend flexoelectric coefficient is found to be rather small, in contrast to common expectations for bent-core molecules. The calculations are in excellent agreement with the experimental values, offering an insight into how molecular parameters contribute to the flexoelectric coefficients and illustrating a huge potential for the prediction of flexoelectric behaviour in bent-core liquid crystals.

  4. Light scattering from liquid crystal director fluctuations in steady magnetic fields up to 25 tesla

    Science.gov (United States)

    Challa, Pavan K.; Curtiss, O.; Williams, J. C.; Twieg, R.; Toth, J.; McGill, S.; Jákli, A.; Gleeson, J. T.; Sprunt, S. N.

    2012-07-01

    We report on homodyne dynamic light scattering measurements of orientational fluctuation modes in both calamitic and bent-core nematic liquid crystals, carried out in the new split-helix resistive magnet at the National High Magnetic Field Laboratory. The relaxation rate and inverse scattered intensity of director fluctuations exhibit a linear dependence on field-squared up to 25 tesla, which is consistent with strictly lowest order coupling of the tensor order parameter Q to field (QαβBαBβ) in the nematic free energy. However, we also observe evidence of field dependence of certain nematic material parameters, an effect which may be expected from the mean field scaling of these quantities with the magnitude of Q and the predicted variation of Q with field.

  5. Crystalline mesoporous metal oxide

    Institute of Scientific and Technical Information of China (English)

    Wenbo Yue; Wuzong Zhou

    2008-01-01

    Since the discovery of many types of mesoporous silicas, such as SBA-15, KIT-6, FDU-12 and SBA-16, porous crystalline transition metal oxides, such as Cr2O3, Co3O4, In2O3, NiO, CeO2, WO3, Fe2O3 and MnO2, have been synthesized using the mesoporous silicas as hard templates. Several synthetic methods have been developed. These new porous materials have high potential applications in catalysis, Li-ion rechargeable batteries and gas sensors. This article gives a brief review of the research of porous crystals of metal oxides in the last four years.

  6. Mesomorphous versus traces of crystallinity: The itraconazole example

    Energy Technology Data Exchange (ETDEWEB)

    Atassi, Faraj, E-mail: fatassi@yahoo.com; Behme, Robert J.; Patel, Phenil J.

    2013-12-20

    Highlights: • Characterizing partially disordered pharmaceuticals is very challenging due to the fact that more than one discrete disordered phase can be present. • Dynamic mechanical analysis and dielectric analysis are extremely helpful in characterizing pharmaceutical mesophases (liquid crystals). • Thermotropic pharmaceutical mesophases, often mistaken as amorphous or partially crystalline, can show different phases of liquid crystallinity at different temperature. • Liquid crystalline pharmaceutical materials often show amorphous behavior along with other characteristics specific to mesomorphous materials. • The thermal and mechanical history of pharmaceutical disordered samples has a significant effect on their phase composition. - Abstract: Characterizing disordered pharmaceutical materials can be challenging, especially materials with partially disordered structures that lose one or two directional order (mesophases) and do not fit the traditional characterization categories of amorphous, crystalline or a combination of the two. Itraconazole, an antifungal agent, was chosen as a model compound that, when quench cooled, exhibits atypical disordered structure. Five different analytical tools were used to map out the molecular structure of this material and how it changes with changing temperature. X-ray diffraction showed some remnant crystallinity while dielectric analysis, dynamic mechanical analysis, DSC and hot stage microscopy gave more detailed molecular structure of the disordered material and explained all temperature related structural changes. The characterization of mesomorphous Itraconazole described here will help characterize a wide range of pharmaceuticals that exhibit thermotropic (temperature induced) mesomorphism at the molecular level.

  7. Liquid crystal drops in suspensions of colloidal plates

    NARCIS (Netherlands)

    Verhoeff, A.A.

    2011-01-01

    This thesis deals with liquid crystalline phases and in particular liquid crystal drops in suspensions of colloidal gibbsite platelets. In Part I we deal with some general aspects of liquid crystalline phases in suspensions of gibbsite platelets, to provide a basic framework for the research describ

  8. H-Bond stabilized columnar discotic liquid crystals

    NARCIS (Netherlands)

    Paraschiv, I.

    2007-01-01

    Since 1977, more than 2300 publications on discotic (disk-like) liquid crystalline materials have appeared. Discotic liquid crystals, which usually consist of polyaromatic molecules surrounded by long peripheral alkyl tails, can form liquid crystalline mesophases in a wide temperature range. Within

  9. Groundwater in crystalline bedrock

    International Nuclear Information System (INIS)

    The aim of this project was to make detailed descriptions of the geological conditions and the different kinds of leakage in some tunnels in Sweden, to be able to describe the presence of ground water in crystalline bedrock. The studies were carried out in TBM tunnels as well as in conventionally drilled and blasted tunnels. Thanks to this, it has been possible to compare the pattern and appearance of ground water leakage in TBM tunnels and in blasted tunnels. On the basis of some experiments in a TBM tunnel, it has been confirmed that a detailed mapping of leakage gives a good picture of the flow paths and their aquiferous qualities in the bedrock. The same picture is found to apply even in cautious blasted tunnels. It is shown that the ground water flow paths in crystalline bedrock are usually restricted to small channels along only small parts of the fractures. This is also true for fracture zones. It has also been found that the number of flow paths generally increases with the degree of tectonisation, up to a given point. With further tectonisation the bedrock is more or less crushed which, along with mineral alteration, leaves only a little space left for the formation of water channels. The largest individual flow paths are usually found in fracture zones. The total amount of ground water leakage per m tunnel is also greater in fracture zones than in the bedrock between the fracture zones. In mapping visible leakage, five classes have been distinguished according to size. Where possible, the individual leak inflow has been measured during the mapping process. The quantification of the leakage classes made in different tunnels are compared, and some quantification standards suggested. A comparison of leakage in different rock types, tectonic zones, fractures etc is also presented. (author)

  10. Bicontinuous liquid crystals

    CERN Document Server

    Lynch, Mathew L

    2005-01-01

    PrefaceIntroduction AcknowledgmentsBicontinuous Cubic Liquid Crystalline Materials: A Historical Perspective and Modern Assessment; Kr̄e LarssonIntermediate Phases; Michael C. Holmes and Marc S. LeaverCubic Phases and Human Skin: Theory and Practice; Steven Hoath and Lars NorlňThe Relationship between Bicontinuous Inverted Cubic Phases and Membrane Fusion; D.P. SiegelAspects of the Differential Geometry and Topology of Bicontinuous Liquid-Crystalline Phases; Robert W. CorkeryNovel L3 Phases and Their Macroscopic Properties; R. Beck and H. HoffmannBicontinuous Cubic Phases of Lipids with Entra

  11. Terahertz Spectroscopy of Crystalline and Non-Crystalline Solids

    DEFF Research Database (Denmark)

    Parrott, Edward P. J.; Fischer, Bernd M.; Gladden, Lynn F.; Zeitler, J. Axel; Jepsen, Peter Uhd

    Terahertz spectroscopy of crystalline and non-crystalline solids is probably one of the most active research fields within the terahertz community. Many potential applications, amongst which spectral recognition is probably one of the most prominent, have significantly stimulated the development of...

  12. Liquid crystals for organic thin-film transistors

    OpenAIRE

    Iino, Hiroaki; Usui, Takayuki; Hanna, Jun-ichi

    2015-01-01

    Crystalline thin films of organic semiconductors are a good candidate for field effect transistor (FET) materials in printed electronics. However, there are currently two main problems, which are associated with inhomogeneity and poor thermal durability of these films. Here we report that liquid crystalline materials exhibiting a highly ordered liquid crystal phase of smectic E (SmE) can solve both these problems. We design a SmE liquid crystalline material, 2-decyl-7-phenyl-[1]benzothieno[3,...

  13. Neutron Transmission Through Crystalline Fe

    Directory of Open Access Journals (Sweden)

    M. Adib

    2005-01-01

    Full Text Available The neutron transmission through crystalline Fe has been calculated for neutron energies in the range 10-4< E<10 eV using an additive formula. The formula permits calculation of the nuclear capture, thermal diffuse and Bragg scattering cross-section as a function of temperature and crystalline form. The obtained agreement between the calculated values and available experimental ones justifies the applicability of the used formula. A feasibility study on using poly-crystalline Fe as a cold neutron filter and a large Fe single crystal as a thermal one is given.

  14. Preparation and evaluation of cellulose-dissolving magnetic ionic liquid

    OpenAIRE

    MURAOKA, Jin; Kamiya, Noriho; Ito, Yuji; ムラオカ, ジン; カミヤ, ノリホ; イトウ, ユウジ; 村岡, 仁; 神谷, 典穂; 伊東, 祐二

    2013-01-01

    Ionic liquids have attracted attention as potential pretreatment agents in cellulosic biomass processing. Here we report on a new magnetic ionic liquid that can dissolve crystalline cellulose and be collected by a magnet.

  15. Nanoscience with liquid crystals from self-organized nanostructures to applications

    CERN Document Server

    Li, Quan

    2014-01-01

    This book focuses on the exciting topic of nanoscience with liquid crystals: from self-organized nanostructures to applications. The elegant self-organized liquid crystalline nanostructures, the synergetic characteristics of liquid crystals and nanoparticles, liquid crystalline nanomaterials, synthesis of nanomaterials using liquid crystals as templates, nanoconfinement and nanoparticles of liquid crystals are covered and discussed, and the prospect of fabricating functional materials is highlighted. Contributions, collecting the scattered literature of the field from leading and active player

  16. Development of novel UV emitting single crystalline film scintillators

    Czech Academy of Sciences Publication Activity Database

    Zorenko, Y.; Gorbenko, V.; Nikl, Martin; Mareš, Jiří A.; Martin, T.; Douissard, P.-A.

    2010-01-01

    Roč. 57, č. 3 (2010), s. 1335-1342. ISSN 0018-9499 R&D Projects: GA ČR GA202/08/0893 Institutional research plan: CEZ:AV0Z10100521 Keywords : Ce 3+ * garnet and perovskite compounds * La 3+ and Sc 3+ dopants * liquid phase epitaxy method * Pr 3+ * single crystalline film scintillators * UV luminescence Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.519, year: 2010

  17. Picosecond laser pulse induced damage in crystalline silicon

    International Nuclear Information System (INIS)

    Picosecond laser pulse irradiation of single crystalline Si can produce severe damage, including amorphisation. Morphology changes are studied by means of optical and high-voltage-electron microscopy and are found to depend on energy fluence, surface orientation, and wavelength. The detailed analysis of the damage distributions and thresholds lead to the conclusion that energy-confinement precedes the introduction of structural changes, which are formed by rapid quenching from the liquid state

  18. neutron transmission through crystalline materials

    International Nuclear Information System (INIS)

    The aim of the present work is to study the neutron transmission through crystalline materials. Therefore a study of pyrolytic graphite (PG) as a highly efficient selective thermal neutron filter and Iron single crystal as a whole one, as well as the applicability of using their polycrystalline powders as a selective cold neutron filters is given. Moreover, the use of PG and iron single crystal as an efficient neutron monochromator is also investigated. An additive formula is given which allows calculating the contribution of the total neutron cross-section including the Bragg scattering from different )(hkl planes to the neutron transmission through crystalline iron and graphite. The formula takes into account their crystalline form. A computer CFe program was developed in order to provide the required calculations for both poly- and single-crystalline iron. The validity of the CFe program was approved from the comparison of the calculated iron cross-section data with the available experimental ones. The CFe program was also adapted to calculate the reflectivity from iron single crystal when it used as a neutron monochromator The computer package GRAPHITE, developed in Neutron Physics laboratory, Nuclear Research Center, has been used in order to provide the required calculations for crystalline graphite in the neutron energy range from 0.1 meV to 10 eV. A Mono-PG code was added to the computer package GRAPHITE in order to calculate the reflectivity from PG crystal when it used as a neutron monochromator.

  19. Diverse topics in crystalline beams

    International Nuclear Information System (INIS)

    Equations of motion are presented, appropriate to interacting charged particles of diverse charge and mass, subject to the external forces produced by various kinds of magnetic fields and radio-frequency (rf) electric fields in storage rings. These equations are employed in the molecular dynamics simulations to study the properties of crystalline beams. The two necessary conditions for the formation and maintenance of crystalline beams are summarized. The transition from ID to 2D, and from 2D to 3D is explored, and the scaling behavior of the heating rates is discussed especially in the high temperature limit. The effectiveness of various cooling techniques in achieving crystalline states has been investigated. Crystalline beams made of two different species of ions via sympathetic cooling are presented, as well as circulating ''crystal balls'' bunched in all directions by magnetic focusing and rf field. By numerically reconstructing the original experimental conditions of the NAP-M ring, it is found that only at extremely low beam intensities, outside of the range of the original measurement, proton particles can form occasionally-passing disks. The proposed New ASTRID ring is shown to be suitable for the formation and maintenance of crystalline beams of all dimensions

  20. 含芳香酯基液晶基元环氧树脂固化 动力学FTIR研究%Curing kinetics of a liquid crystalline epoxy with the aromatic ester mesogen by FTIR

    Institute of Scientific and Technical Information of China (English)

    陈立新; 王汝敏; 蓝立文; 徐亚洪; 廖建伟

    2001-01-01

    应用DTA分析研究了含液晶基元的环氧化物-对羟基苯甲酸对苯二酚二缩水甘油醚与四种芳香胺类固化剂的固化行为,选择了4,4’-二氨基二苯甲烷为固化剂。根据环氧树脂自催化固化反应模型和氨基氢等活性假设,利用傅立叶变换红外光谱法研究了液晶环氧/4,4’-二氨基二苯甲烷体系在90℃、120℃、140℃恒温固化时的动力学行为。结果表明,在反应程度低于40%时,符合自催化模型。%The curing processes of diglycidlether of 4 - hydroxyphenyl - 4 - hydroxybenzoate(PHBHQ) with four different amine curing agents were studied by means of the DTA. A suitable curing agent ,4,4'-diaminodiphenyl methane( DDM) was selected as well. Based on the self- catalyzed curing model of epoxy resin and equal activity of hydrogen amino , the isothermal curing processes of PHBHQ/ DDM liquid system at 90℃,120℃,140℃ were monitored by Fourier Transform Infra-Red Spectrum(FTIR). The result showed that the curing process was accorded with the self- catalyzed curing model when the reaction extent bellowed 40%.

  1. Renal tumor with alpha b crystallin expression

    OpenAIRE

    Kim, Mee-Seon; Lee, Hyoun Wook; Lee, Eun Hee

    2015-01-01

    In human, proximal convoluted tubules and thin limbs of Henle show expression of αB crystallin. Renal cell carcinoma also showed expression of αB crystallin in previous reports. We aimed to study the association between αB crystallin expression and renal cell carcinoma and urothelial carcinoma. Furthermore, we also investigated αB crystallin expression depending on the subtype of renal cell carcinoma and examined the relationship between αB crystallin expression and survival in patients with ...

  2. Single crystalline mesoporous silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Hochbaum, Allon; Dargas, Daniel; Hwang, Yun Jeong; Yang, Peidong

    2009-08-18

    Herein we demonstrate a novel electroless etching synthesis of monolithic, single-crystalline, mesoporous silicon nanowire arrays with a high surface area and luminescent properties consistent with conventional porous silicon materials. The photoluminescence of these nanowires suggest they are composed of crystalline silicon with small enough dimensions such that these arrays may be useful as photocatalytic substrates or active components of nanoscale optoelectronic devices. A better understanding of this electroless route to mesoporous silicon could lead to facile and general syntheses of different narrow bandgap semiconductor nanostructures for various applications.

  3. Single crystalline mesoporous silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Hochbaum, A.I.; Gargas, Daniel; Jeong Hwang, Yun; Yang, Peidong

    2009-08-04

    Herein we demonstrate a novel electroless etching synthesis of monolithic, single-crystalline, mesoporous silicon nanowire arrays with a high surface area and luminescent properties consistent with conventional porous silicon materials. These porous nanowires also retain the crystallographic orientation of the wafer from which they are etched. Electron microscopy and diffraction confirm their single-crystallinity and reveal the silicon surrounding the pores is as thin as several nanometers. Confocal fluorescence microscopy showed that the photoluminescence (PL) of these arrays emanate from the nanowires themselves, and their PL spectrum suggests that these arrays may be useful as photocatalytic substrates or active components of nanoscale optoelectronic devices.

  4. Self-diffusion in the non-Newtonian regime of shearing liquid crystal model systems based on the Gay-Berne potential

    Science.gov (United States)

    Sarman, Sten; Wang, Yong-Lei; Laaksonen, Aatto

    2016-02-01

    The self-diffusion coefficients of nematic phases of various model systems consisting of regular convex calamitic and discotic ellipsoids and non-convex bodies such as bent-core molecules and soft ellipsoid strings have been obtained as functions of the shear rate in a shear flow. Then the self-diffusion coefficient is a second rank tensor with three different diagonal components and two off-diagonal components. These coefficients were found to be determined by a combination of two mechanisms, which previously have been found to govern the self-diffusion of shearing isotropic liquids, namely, (i) shear alignment enhancing the diffusion in the direction parallel to the streamlines and hindering the diffusion in the perpendicular directions and (ii) the distortion of the shell structure in the liquid whereby a molecule more readily can escape from a surrounding shell of nearest neighbors, so that the mobility increases in every direction. Thus, the diffusion parallel to the streamlines always increases with the shear rate since these mechanisms cooperate in this direction. In the perpendicular directions, these mechanisms counteract each other so that the behaviour becomes less regular. In the case of the nematic phases of the calamitic and discotic ellipsoids and of the bent core molecules, mechanism (ii) prevails so that the diffusion coefficients increase. However, the diffusion coefficients of the soft ellipsoid strings decrease in the direction of the velocity gradient because the broadsides of these molecules are oriented perpendicularly to this direction due the shear alignment (i). The cross coupling coefficient relating a gradient of tracer particles in the direction of the velocity gradient and their flow in the direction of the streamlines is negative and rather large, whereas the other coupling coefficient relating a gradient in the direction of the streamlines and a flow in the direction of the velocity gradient is very small.

  5. Self-diffusion in the non-Newtonian regime of shearing liquid crystal model systems based on the Gay-Berne potential

    International Nuclear Information System (INIS)

    The self-diffusion coefficients of nematic phases of various model systems consisting of regular convex calamitic and discotic ellipsoids and non-convex bodies such as bent-core molecules and soft ellipsoid strings have been obtained as functions of the shear rate in a shear flow. Then the self-diffusion coefficient is a second rank tensor with three different diagonal components and two off-diagonal components. These coefficients were found to be determined by a combination of two mechanisms, which previously have been found to govern the self-diffusion of shearing isotropic liquids, namely, (i) shear alignment enhancing the diffusion in the direction parallel to the streamlines and hindering the diffusion in the perpendicular directions and (ii) the distortion of the shell structure in the liquid whereby a molecule more readily can escape from a surrounding shell of nearest neighbors, so that the mobility increases in every direction. Thus, the diffusion parallel to the streamlines always increases with the shear rate since these mechanisms cooperate in this direction. In the perpendicular directions, these mechanisms counteract each other so that the behaviour becomes less regular. In the case of the nematic phases of the calamitic and discotic ellipsoids and of the bent core molecules, mechanism (ii) prevails so that the diffusion coefficients increase. However, the diffusion coefficients of the soft ellipsoid strings decrease in the direction of the velocity gradient because the broadsides of these molecules are oriented perpendicularly to this direction due the shear alignment (i). The cross coupling coefficient relating a gradient of tracer particles in the direction of the velocity gradient and their flow in the direction of the streamlines is negative and rather large, whereas the other coupling coefficient relating a gradient in the direction of the streamlines and a flow in the direction of the velocity gradient is very small

  6. Self-diffusion in the non-Newtonian regime of shearing liquid crystal model systems based on the Gay-Berne potential

    Energy Technology Data Exchange (ETDEWEB)

    Sarman, Sten, E-mail: sarman@ownit.nu; Wang, Yong-Lei; Laaksonen, Aatto [Arrhenius Laboratory, Department of Materials and Environmental Chemistry, Stockholm University, 106 91 Stockholm (Sweden)

    2016-02-07

    The self-diffusion coefficients of nematic phases of various model systems consisting of regular convex calamitic and discotic ellipsoids and non-convex bodies such as bent-core molecules and soft ellipsoid strings have been obtained as functions of the shear rate in a shear flow. Then the self-diffusion coefficient is a second rank tensor with three different diagonal components and two off-diagonal components. These coefficients were found to be determined by a combination of two mechanisms, which previously have been found to govern the self-diffusion of shearing isotropic liquids, namely, (i) shear alignment enhancing the diffusion in the direction parallel to the streamlines and hindering the diffusion in the perpendicular directions and (ii) the distortion of the shell structure in the liquid whereby a molecule more readily can escape from a surrounding shell of nearest neighbors, so that the mobility increases in every direction. Thus, the diffusion parallel to the streamlines always increases with the shear rate since these mechanisms cooperate in this direction. In the perpendicular directions, these mechanisms counteract each other so that the behaviour becomes less regular. In the case of the nematic phases of the calamitic and discotic ellipsoids and of the bent core molecules, mechanism (ii) prevails so that the diffusion coefficients increase. However, the diffusion coefficients of the soft ellipsoid strings decrease in the direction of the velocity gradient because the broadsides of these molecules are oriented perpendicularly to this direction due the shear alignment (i). The cross coupling coefficient relating a gradient of tracer particles in the direction of the velocity gradient and their flow in the direction of the streamlines is negative and rather large, whereas the other coupling coefficient relating a gradient in the direction of the streamlines and a flow in the direction of the velocity gradient is very small.

  7. Topological Twistons in Crystalline Polyethylene

    OpenAIRE

    D. Bazeia; Ventura, E.

    1998-01-01

    We introduce an alternate model to describe twistons in crystalline polyethylene. The model couples torsional and longitudinal degrees of freedom and appears as an extension of a model that describes only the torsional motion. We find exact solutions that describe stable topological twistons, in good agreement with the torsional and longitudinal interactions in polyethylene.

  8. Liquid crystals in biotribology synovial joint treatment

    CERN Document Server

    Ermakov, Sergey; Eismont, Oleg; Nikolaev, Vladimir

    2016-01-01

    This book summarizes the theoretical and experimental studies confirming the concept of the liquid-crystalline nature of boundary lubrication in synovial joints. It is shown that cholesteric liquid crystals in the synovial liquid play a significant role in the mechanism of intra-articular friction reduction. The results of structural, rheological and tribological research of the creation of artificial synovial liquids - containing cholesteric liquid crystals in natural synovial liquids - are described. These liquid crystals reproduce the lubrication properties of natural synovia and provide a high chondroprotective efficiency. They were tested in osteoarthritis models and in clinical practice.

  9. J-like liquid-crystalline and crystalline states of polyaniline revealed by thin, highly crystalline, and strongly oriented films

    Czech Academy of Sciences Publication Activity Database

    Gospodinova, Natalia; Tomšík, Elena; Omelchenko, Olga

    2014-01-01

    Roč. 118, č. 29 (2014), s. 8901-8904. ISSN 1520-6106 R&D Projects: GA ČR(CZ) GA13-00270S Institutional support: RVO:61389013 Keywords : J-aggregates * organic semiconductors * polyaniline Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.302, year: 2014

  10. Liquids and liquid mixtures

    CERN Document Server

    Rowlinson, J S; Baldwin, J E; Buckingham, A D; Danishefsky, S

    2013-01-01

    Liquids and Liquid Mixtures, Third Edition explores the equilibrium properties of liquids and liquid mixtures and relates them to the properties of the constituent molecules using the methods of statistical thermodynamics. Topics covered include the critical state, fluid mixtures at high pressures, and the statistical thermodynamics of fluids and mixtures. This book consists of eight chapters and begins with an overview of the liquid state and the thermodynamic properties of liquids and liquid mixtures, including vapor pressure and heat capacities. The discussion then turns to the thermodynami

  11. Liquid crystal applications and uses, v.3

    CERN Document Server

    Bahadur, Birenda

    1992-01-01

    This book reviews comprehensively the technological, scientific, artistic and medical applications of liquid crystals. It starts with the basics of liquid crystals and covers electro-optical, thermo-optical, colour, polymeric, lyotropic, and scientific applications of liquid crystalline materials. It discusses the fabrication and operational principles of a full range of liquid crystal displays including dynamic scattering, twisted nematic, supertwisted nematic, dichroic, smectic A, ferroelectric, polymer dispersed, light valve, active matrix, etc., in detail. It also covers the emerging appli

  12. Liquid crystal applications and uses, v.2

    CERN Document Server

    Bahadur, Birenda

    1991-01-01

    This book reviews comprehensively the technological, scientific, artistic and medical applications of liquid crystals. It starts with the basics of liquid crystals and covers electro-optical, thermo-optical, colour, polymeric, lyotropic, and scientific applications of liquid crystalline materials. It discusses the fabrication and operational principles of a full range of liquid crystal displays including dynamic scattering, twisted nematic, supertwisted nematic, dichroic, smectic A, ferroelectric, polymer dispersed, light valve, active matrix, etc., in detail. It also covers the emerging appli

  13. Liquid crystal applications and uses, v.1

    CERN Document Server

    Bahadur, Birenda

    1990-01-01

    This book reviews comprehensively the technological, scientific, artistic and medical applications of liquid crystals. It starts with the basics of liquid crystals and covers electro-optical, thermo-optical, colour, polymeric, lyotropic, and scientific applications of liquid crystalline materials. It discusses the fabrication and operational principles of a full range of liquid crystal displays including dynamic scattering, twisted nematic, supertwisted nematic, dichroic, smectic A, ferroelectric, polymer dispersed, light valve, active matrix, , in detail. It also covers the emerging applicati

  14. Superfluorinated Ionic Liquid Crystals Based on Supramolecular, Halogen-Bonded Anions

    OpenAIRE

    Cavallo, Gabriella; Terraneo, Giancarlo; Monfredini, Alessandro; Saccone, Marco; Priimagi, Arri; Pilati, Tullio; Resnati, Giuseppe; Metrangolo, Pierangelo; Bruce, Duncan W

    2016-01-01

    Unconventional ionic liquid crystals in which the liquid crystallinity is enabled by halogen-bonded supramolecular anions [CnF2n+1-I···I···I-CnF2n+1]- are reported. The material system is unique in many ways, demonstrating for the first time 1)ionic, halogen-bonded liquid crystals, and 2)imidazolium-based ionic liquid crystals in which the occurrence of liquid crystallinity is not driven by the alkyl chains of the cation.

  15. EELS from organic crystalline materials

    International Nuclear Information System (INIS)

    We report the use of the electron energy loss spectroscopy (EELS) for providing light element chemical composition information from organic, crystalline pharmaceutical materials including theophylline and paracetamol and discuss how this type of data can complement transmission electron microscopy (TEM) imaging and electron diffraction when investigating polymorphism. We also discuss the potential for the extraction of bonding information using electron loss near-edge structure (ELNES)

  16. The crystalline sponge method updated

    Directory of Open Access Journals (Sweden)

    Manabu Hoshino

    2016-03-01

    Full Text Available Crystalline sponges are porous metal complexes that can absorb and orient common organic molecules in their pores and make them observable by conventional X-ray structure analysis (crystalline sponge method. In this study, all of the steps in the crystalline sponge method, including sponge crystal preparation, pore–solvent exchange, guest soaking, data collection and crystallographic analysis, are carefully examined and thoroughly optimized to provide reliable and meaningful chemical information as chemical crystallography. Major improvements in the method have been made in the guest-soaking and data-collection steps. In the soaking step, obtaining a high site occupancy of the guest is particularly important, and dominant parameters for guest soaking (e.g. temperature, time, concentration, solvents therefore have to be optimized for every sample compound. When standard conditions do not work, a high-throughput method is useful for efficiently optimizing the soaking conditions. The X-ray experiments are also carefully re-examined. Significant improvement of the guest data quality is achieved by complete data collection at high angle regions. The appropriate disorder treatment of the most flexible ZnI2 portions of the host framework and refinement of the solvents filling the remaining void are also particularly important for obtaining better data quality. A benchmark test for the crystalline sponge method toward an achiral molecule is proposed with a guaiazulene guest, in which the guest structure (with ∼ 100% site occupancy is refined without applying any restraints or constraints. The obtained data quality with Rint = 0.0279 and R1 = 0.0379 is comparable with that of current conventional crystallographic analysis for small molecules. Another benchmark test for this method toward a chiral molecule is also proposed with a santonin guest. The crystallographic data obtained [Rint = 0.0421, R1 = 0.0312, Flack (Parsons = −0.0071 (11

  17. The crystalline sponge method updated.

    Science.gov (United States)

    Hoshino, Manabu; Khutia, Anupam; Xing, Hongzhu; Inokuma, Yasuhide; Fujita, Makoto

    2016-03-01

    Crystalline sponges are porous metal complexes that can absorb and orient common organic molecules in their pores and make them observable by conventional X-ray structure analysis (crystalline sponge method). In this study, all of the steps in the crystalline sponge method, including sponge crystal preparation, pore-solvent exchange, guest soaking, data collection and crystallographic analysis, are carefully examined and thoroughly optimized to provide reliable and meaningful chemical information as chemical crystallography. Major improvements in the method have been made in the guest-soaking and data-collection steps. In the soaking step, obtaining a high site occupancy of the guest is particularly important, and dominant parameters for guest soaking (e.g. temperature, time, concentration, solvents) therefore have to be optimized for every sample compound. When standard conditions do not work, a high-throughput method is useful for efficiently optimizing the soaking conditions. The X-ray experiments are also carefully re-examined. Significant improvement of the guest data quality is achieved by complete data collection at high angle regions. The appropriate disorder treatment of the most flexible ZnI2 portions of the host framework and refinement of the solvents filling the remaining void are also particularly important for obtaining better data quality. A benchmark test for the crystalline sponge method toward an achiral molecule is proposed with a guaiazulene guest, in which the guest structure (with ∼ 100% site occupancy) is refined without applying any restraints or constraints. The obtained data quality with R int = 0.0279 and R 1 = 0.0379 is comparable with that of current conventional crystallographic analysis for small molecules. Another benchmark test for this method toward a chiral molecule is also proposed with a santonin guest. The crystallographic data obtained [R int = 0.0421, R 1 = 0.0312, Flack (Parsons) = -0.0071 (11)] represents the

  18. The crystalline sponge method updated

    Science.gov (United States)

    Hoshino, Manabu; Khutia, Anupam; Xing, Hongzhu; Inokuma, Yasuhide; Fujita, Makoto

    2016-01-01

    Crystalline sponges are porous metal complexes that can absorb and orient common organic molecules in their pores and make them observable by conventional X-ray structure analysis (crystalline sponge method). In this study, all of the steps in the crystalline sponge method, including sponge crystal preparation, pore–solvent exchange, guest soaking, data collection and crystallographic analysis, are carefully examined and thoroughly optimized to provide reliable and meaningful chemical information as chemical crystallography. Major improvements in the method have been made in the guest-soaking and data-collection steps. In the soaking step, obtaining a high site occupancy of the guest is particularly important, and dominant parameters for guest soaking (e.g. temperature, time, concentration, solvents) therefore have to be optimized for every sample compound. When standard conditions do not work, a high-throughput method is useful for efficiently optimizing the soaking conditions. The X-ray experiments are also carefully re-examined. Significant improvement of the guest data quality is achieved by complete data collection at high angle regions. The appropriate disorder treatment of the most flexible ZnI2 portions of the host framework and refinement of the solvents filling the remaining void are also particularly important for obtaining better data quality. A benchmark test for the crystalline sponge method toward an achiral molecule is proposed with a guaiazulene guest, in which the guest structure (with ∼ 100% site occupancy) is refined without applying any restraints or constraints. The obtained data quality with R int = 0.0279 and R 1 = 0.0379 is comparable with that of current conventional crystallographic analysis for small molecules. Another benchmark test for this method toward a chiral molecule is also proposed with a santonin guest. The crystallographic data obtained [R int = 0.0421, R 1 = 0.0312, Flack (Parsons) = −0.0071 (11)] represents the

  19. Overview of Crystalline Color Superconductors

    CERN Document Server

    Mannarelli, Massimo

    2015-01-01

    Inhomogeneous phases may appear when a stress is applied to a system and the system can minimize the free energy breaking the rotational invariance. Various examples are known in Nature of this sort, as the paramagnetic to ferromagnetic phase transition, or the fluid/solid phase transition. If the rotational symmetry is broken down to a discrete symmetry, the system is typically named a crystal. We breifly review crystalline color superconductors, which arise in cold quark matter with mismatched Fermi spheres.

  20. Solubility of crystalline thorium dioxide

    International Nuclear Information System (INIS)

    The solubility of thorium oxides of different crystallinity is investigated at 25 C by different experimental approaches. The dissolution of bulk crystalline ThO2(cr) is a very slow process and the Th(IV) concentrations measured after one year at pH 1-3 in 0.1 and 0.5 M HCl-NaCl solutions do not represent equilibrium data. Coulometric titration of thorium nitrate solutions in the low pH range of 1.5-2.5 leads to the formation of microcrystalline ThO2.xH2O(mcr) particles which subsequently agglomerate to a precipitate. The solubility of this solid, in equilibrium with Th4+(aq), is measured from the oversaturation direction. The solubility product is determined to be log K'sp = -49.9±0.4 in 0.5 M NaCl corresponding to log Kspo = -53.2±0.4 (converted to I = 0 with the SIT). It is close to the thermochemical value for ThO2(cr) and about 6 orders of magnitude lower than that of X-ray amorphous Th(IV) hydroxide or hydrous oxide. The differences in the solubility products are discussed with regard to the particle size and compared with analogous data for U(IV), Np(IV) and Pu(IV). Above the threshold of hydrolysis of Th4+ at pH > 2.5, the dissolution of microcrystalline ThO2.xH2O(mcr) is found to be irreversible. In near-neutral to alkaline solutions, the measured thorium concentrations approach those of amorphous Th(OH)4(am). Similar results are obtained with crystalline ThO2(cr) in 0.5 M NaCl-NaOH solutions. The solubility is not controlled by the bulk crystalline solid but by amorphous fractions on the surface. (orig.)

  1. Rheological behavior of polypropylene melt modified with main chain thermotropic liquid crystalline polymer through high speed extrusion%主链型液晶高分子改善聚丙烯熔体高速挤出的流变行为

    Institute of Scientific and Technical Information of China (English)

    刘祥贵; 李金亮; 吴其晔

    2012-01-01

    The authors studied the influence of main chain thermotropic liquid crystalline polymer(TLCP) on rheological properties of polypropylene random copolymer(PPR) through high speed extrusion by a constant speed double-capillary rheometer. The helix distortion of the PPR melt was caused by stress concentration and transverse circulation flow at the die entrance. The samples of PPR4220/TLCP were prepared with in-situ fibrillation. The TLCP phase oriented obviously in the tension field and the degree of orientation rose first and then dropped with increasing stretch rate. The oriented TLCP could significantly weaken the helix distortion of melt extrudates, alleviate unstable flow and stress concentration at the die entrance and improve the melt viscoelasticity. The higher the TLCP content, the better the improvement effect.%采用恒速型双毛细管流变仪研究了主链型热致液晶对无规共聚聚丙烯(PPR)熔体高速挤出流变性能的影响.PPR熔体螺纹状畸变是由口模入口区的应力集中效应和横向环流造成的;利用原位成纤法制备PPR/热致液晶聚合物(TLCP)试样,TLCP在拉伸场中明显取向,随拉伸速率增大,取向程度先增大后减小;取向的TLCP明显减弱熔体挤出物的螺纹畸变现象,改善熔体在口模入口区的不稳定流动和应力集中效应,改善熔体的黏弹性;TLCP含量越多,改善效果越明显.

  2. Rheological behavior of polypropylene melt modified with main chain thermotropic liquid crystalline polymer through high speed extrusion%主链型液晶高分子改善聚丙烯熔体高速挤出的流变行为

    Institute of Scientific and Technical Information of China (English)

    刘祥贵; 李金亮; 吴其晔

    2011-01-01

    The authors studied the influence of main chain thermotropic liquid crystalline polymer(TLCP) on rheological properties of polypropylene random copolymer(PPR) through high speed extrusion by a constant speed double-capillary rheometer. The helix distortion of the PPR melt was caused by stress concentration and transverse circulation flow at the die entrance. The samples of PPR4220/TLCP were prepared with in-situ fibrillation. The TLCP phase oriented obviously in the tension field and the degree of orientation rose first and then dropped with increasing stretch rate.The oriented TLCP could significantly weaken the helix distortion of melt extrudates,alleviate unstable flow and stress concentration at the die entrance and improve the melt viscoelasticity. The higher the TLCP content, the better the improvement effect.%采用恒速型双毛细管流变仪研究了主链型热致液晶对无规共聚聚丙烯(PPR)熔体高速挤出流变性能的影响.PPR熔体螺纹状畸变是由口模入口区的应力集中效应和横向环流造成的;利用原位成纤法制备PPR/热致液晶聚合物(TLCP)试样,TLCP在拉伸场中明显取向,随拉伸速率增大,取向程度先增大后减小;取向的TLCP明显减弱熔体挤出物的螺纹畸变现象,改善熔体在口模入口区的不稳定流动和应力集中效应,改善熔体的黏弹性;TLCP含量越多,改善效果越明显.

  3. Grouting methodology in crystalline rock

    International Nuclear Information System (INIS)

    For this paper, an initial literature review was conducted to investigate the potential applications of grouting technology for geological disposal of high level radioactive waste (hereafter called geological disposal), and the potential grouting material for each application. The results show the necessity of using suspension grout, such as cement-based grout, during excavation work, especially deep underground. Next, the method to achieve highly effective seals in crystalline rock with cement grout is studied. To enhance the sealing quality, cement grout should penetrate into very fine fractures, e.g. less than 100 μm aperture. In the case of suspension grout, clogging with grout at the openings of rock fractures, especially fine fractures, tends to occur, which results in poor grout penetration. A laboratory experiment was conducted to investigate the clogging phenomenon; the results suggest that high injection pressures could be effective to prevent clogging. Finally, focusing on pre-excavation grouting for horizontal tunnels in crystalline rock, the effective grout hole patterns for achieving high quality sealing was studied. A series of theoretical calculations for water inflow and cost studies were conducted. The results indicate that a dense arrangement of grout holes in a relatively narrow area around a tunnel section, as practised in the Nordic countries, is favorable in hard crystalline rock. (author)

  4. Biocompatibility of crystalline opal nanoparticles

    Directory of Open Access Journals (Sweden)

    Hernández-Ortiz Marlen

    2012-10-01

    Full Text Available Abstract Background Silica nanoparticles are being developed as a host of biomedical and biotechnological applications. For this reason, there are more studies about biocompatibility of silica with amorphous and crystalline structure. Except hydrated silica (opal, despite is presents directly and indirectly in humans. Two sizes of crystalline opal nanoparticles were investigated in this work under criteria of toxicology. Methods In particular, cytotoxic and genotoxic effects caused by opal nanoparticles (80 and 120 nm were evaluated in cultured mouse cells via a set of bioassays, methylthiazolyldiphenyl-tetrazolium-bromide (MTT and 5-bromo-2′-deoxyuridine (BrdU. Results 3T3-NIH cells were incubated for 24 and 72 h in contact with nanocrystalline opal particles, not presented significant statistically difference in the results of cytotoxicity. Genotoxicity tests of crystalline opal nanoparticles were performed by the BrdU assay on the same cultured cells for 24 h incubation. The reduction of BrdU-incorporated cells indicates that nanocrystalline opal exposure did not caused unrepairable damage DNA. Conclusions There is no relationship between that particles size and MTT reduction, as well as BrdU incorporation, such that the opal particles did not induce cytotoxic effect and genotoxicity in cultured mouse cells.

  5. Controlling growth density and patterning of single crystalline silicon nanowires

    International Nuclear Information System (INIS)

    This study examines the usage of well-patterned Au nanoparticles (NPs) as a catalyst for one-dimensional growth of single crystalline Si nanowires (NWs) through the vapor-liquid-solid (VLS) mechanism. The study reports the fabrication of monolayer Au NPs through the self-assembly of Au NPs on a 3-aminopropyltrimethoxysilane (APTMS)-modified silicon substrate. Results indicate that the spin coating time of Au NPs plays a crucial role in determining the density of Au NPs on the surface of the silicon substrate and the later catalysis growth of Si NWs. The experiments in this study employed optical lithography to pattern Au NPs, treating them as a catalyst for Si NW growth. The patterned Si NW structures easily produced and controlled Si NW density. This approach may be useful for further studies on single crystalline Si NW-based nanodevices and their properties.

  6. Functional photochromic methylhydrosiloxane-based side chain liquid crystalline polymers

    Czech Academy of Sciences Publication Activity Database

    Tóth-Katona, T.; Cigl, Martin; Fodor-Csorba, K.; Hamplová, Věra; Jánossy, I.; Kašpar, Miroslav; Vojtylová, Terézia; Hampl, F.; Bubnov, Alexej

    2014-01-01

    Roč. 215, č. 8 (2014), s. 742-752. ISSN 1022-1352 R&D Projects: GA ČR GA13-14133S; GA MŠk 7AMB13PL038 Grant ostatní: AVČR(CZ) M100101204 Institutional support: RVO:68378271 Keywords : azo-polymers * nematics * polysiloxanes * self-assembly Subject RIV: JJ - Other Materials Impact factor: 2.616, year: 2014

  7. Dancing with light advances in photofunctional liquid-crystalline materials

    CERN Document Server

    Yu, Haifeng

    2015-01-01

    Recent progress in this field indicates that integrating photochromic molecules into LC materials enables one to photo-manipulate unique features such as photoinduced phase transition, photocontrolled alignment and phototriggered molecular cooperative motion, leading to their novel applications beyond displays. This book introduces readers to this field, from the primary- to the advanced level in photoresponsive LC materials. The subject is introduced step-by-step, including the basic knowledge of LCs, photoresponsive properties of LCs, and their detailed performances in the form of low-molecu

  8. Lyotropic liquid crystalline nanoparticles of CoQ10

    DEFF Research Database (Denmark)

    Swarnakar, Nitin K; Thanki, Kaushik; Jain, Sanyog

    2014-01-01

    ) and phytantriol (PLCQ). Exhaustive optimization of the process variables was carried out, and optimized lyophilized formulations were found to have particle sizes of 140.45 ± 5.47 nm and 238.42 ± 8.35 nm and a polydispersity index (PDI) of 0.15 ± 0.01 and 0.22 ± 0.03 for GLCQ and PLCQ, respectively...

  9. High rectification in organic diodes based on liquid crystalline phthalocyanines.

    Science.gov (United States)

    Apostol, Petru; Eccher, Juliana; Dotto, Marta Elisa Rosso; Costa, Cassiano Batesttin; Cazati, Thiago; Hillard, Elizabeth A; Bock, Harald; Bechtold, Ivan H

    2015-12-28

    The optical and electrical properties of mesogenic metal-free and metalated phthalocyanines (PCs) with a moderately sized and regioregular alkyl periphery were investigated. In solution, the individualized molecules show fluorescence lifetimes of 4-6 ns in THF. When deposited as solid thin films the materials exhibit significantly shorter fluorescence lifetimes with bi-exponential decay (1.4-1.8 ns; 0.2-0.4 ns) that testify to the formation of aggregates viaπ-π intermolecular interactions. In diode structures, their pronounced columnar order outbalances the unfavorable planar alignment and leads to excellent rectification behavior. Field-dependent charge carrier mobilities are obtained from the J-V curves in the trap-limited space-charge-limited current regime and demonstrate that the metalated PCs display an improved electrical response with respect to the metal-free homologue. The excited-state lifetime characterization suggest that the π-π intermolecular interactions are stronger for the metal-free PC, confirming that the metallic centre plays an important role in the charge transport inside these materials. PMID:26585027

  10. Liquid-Crystalline Ternary Rare-Earth Complexes

    OpenAIRE

    Knyazev, Andrey A.; Galyametdinov, Yury G.; Goderis, Bart; Driesen, Kris; Goossens, Karel; Görller-Walrand, Christiane; Binnemans, Koen; Cardinaels, Thomas

    2008-01-01

    The thermal behavior of the metallomesogens [Ln(C12C16dbm)3(phen)], where Ln = La, Nd, Eu, Gd, Tb, Dy, Er, Yb; C12C16dbm = 1-(4-dodecyloxyphenyl)-3-(4-hexadecyloxyphenyl)-propane-1,3-dionate; phen = 1,10-phenanthroline) was investigated. The complexes of the light lanthanides (Ln = La, Nd) are not mesomorphic, whereas the complexes of the heavy lanthanides (Ln = Eu, Gd, Tb, Dy, Er, Yb) exhibit a monotropic smectic A phase. A model for the molecular organization of the molecules in the smectic...

  11. Cellulose nanorods in liquid crystalline elastomers for improved actuators

    OpenAIRE

    Pontes, Rita Valério

    2014-01-01

    Nanotechnology plays a central role in ‘tailoring’ materials’ properties and thus improving its performances for a wide range of applications. Coupling nature nano-objects with nanotechnology results in materials with enhanced functionalities. The main objective of this master thesis was the synthesis of nanocrystalline cellulose (NCCs) and its further incorporation in a cellulosic matrix, in order to produce a stimuli-responsive material to moisture. The induced behaviour (bending/unbendi...

  12. Electro-Rheological Effect of Liquid Crystalline Glycerin Derivative

    Institute of Scientific and Technical Information of China (English)

    N. Nakamura

    2005-01-01

    @@ 1Introduction Rheological property of a material is changed reversibly by an addition of electric field. The property is called electro-rheological (ER) effect, and the materials showed such an effect are named ER fluid in general.It is expected that the fluids are available for an application of mechanical fields like braking system, shock absorber one, and so on.

  13. Liquid-Crystalline Collapse of Pulmonary Surfactant Monolayers

    OpenAIRE

    William R Schief; Antia, Meher; Discher, Bohdana M.; Hall, Stephen B.; Vogel, Viola

    2003-01-01

    During exhalation, the surfactant film of lipids and proteins that coats the alveoli in the lung is compressed to high surface pressures, and can remain metastable for prolonged periods at pressures approaching 70 mN/m. Monolayers of calf lung surfactant extract (CLSE), however, collapse in vitro, during an initial compression at ∼45 mN/m. To gain information on the source of this discrepancy, we investigated how monolayers of CLSE collapse from the interface. Observations with fluorescence, ...

  14. Photoorientation of a liquid crystalline polyester with azobenzene side groups

    DEFF Research Database (Denmark)

    Zebger, I; Rutloh, M; Hoffmann, U;

    2002-01-01

    The photoorientation process in a polyester with 4-cyano-4'-alkoxyazobenzene side group and long methylene spacers in the side and the main-chain was studied as a function of irradiation with linearly polarized light of 488 nm under systematic variation of the power density and temperature. This...

  15. Anomalous phase sequence in new chiral liquid crystalline materials

    Czech Academy of Sciences Publication Activity Database

    Podoliak, Natalia; Novotná, Vladimíra; Kašpar, Miroslav; Hamplová, Věra; Glogarová, Milada; Pociecha, D.

    2014-01-01

    Roč. 41, č. 2 (2014), s. 176-183. ISSN 0267-8292 R&D Projects: GA ČR GA13-14133S; GA ČR(CZ) GAP204/11/0723 Grant ostatní: AVČR(CZ) M100101211 Institutional support: RVO:68378271 Keywords : chiral chain * lactate unit * TGBA phase * re-entrancy * TGBC phase Subject RIV: JJ - Other Materials Impact factor: 2.486, year: 2014

  16. Computer Simulations of Simple Liquids with Tetrahedral Local Order : the Supercooled Liquid, Solids and Phase Transitions

    OpenAIRE

    Elenius, Måns

    2009-01-01

    The understanding of complex condensed matter systems is an area of intense study. In this thesis, some properties of simple liquids with strong preference for tetrahedral local ordering are explored. These liquids are amenable to supercooling, and give complex crystalline structures on eventual crystallisation. All liquids studied are simple, monatomic and are similar to real metallic liquids. The vibrational density of states of a glass created in simulation is calculated. We show a corresp...

  17. Examination of the anisotropy of the wetting behaviour of liquid Al-Cu alloys on single crystalline oriented Al{sub 2}O{sub 3}-substrates; Untersuchung der Anisotropie im Benetzungsverhalten fluessiger Al-Cu Legierungen auf einkristallinen orientierten Al{sub 2}O{sub 3}-Substraten

    Energy Technology Data Exchange (ETDEWEB)

    Schmitz, Julianna

    2011-02-04

    The wetting behaviour of liquid Al-Cu alloys and pure metals on oriented single crystalline Al{sub 2}O{sub 3}-substrates was examined, utilising the sessile drop technique. Measurements were performed at moderate temperatures of 1100 C, where the alloys are liquid. Different Al{sub 2}O{sub 3}-surfaces were studied, which are terminated by the crystallographic planes (0001), (11 anti 20), and (1 anti 102), also called C-, A-, and R-surfaces. After deposition, pure Cu-droplets show an exponential increase of the wetting angle to a value of about 115 for all investigated Al{sub 2}O{sub 3}-surfaces. The timescale of this increase is of the order of 100 s. The effect of surface- and interfacial energies on the wetting angle is discussed considering Young's equation. The most probable reason for its time-dependence seems to be an increase of the interfacial energy due to deoxidation of the droplet. Therefore it is reasonable to regard the isotropic contact angle value as the intrinsic one of the Cu/Al{sub 2}O{sub 3} system. In contrast, the wetting angle of pure Al metal with the different Al{sub 2}O{sub 3}-substrates shows a qualitatively different behaviour. In this system, it rises from about 90 to 115 roughly for C-substrates, twice as fast as in the Cu case but to a comparable value. On the other substrates a wetting angle of about 90 establishes immediately, and no pronounced time dependence is obvious. In order to study changes in the wetting behaviour of Al-Cu-alloys, which is isotropic for Cu and anisotropic for Al-rich alloys, contact angles of Al{sub 50}Cu{sub 50}, Al{sub 30}Cu{sub 70} und Al{sub 17}Cu{sub 83} on Al{sub 2}O{sub 3} were determined. For each alloy composition the wetting angle is about 120 after 300 s. The initial values on distinct surfaces hardly differ and become non-wetting with increasing Cu-content. Hence, anisotropy decreases. To determine the work of adhesion of the solid-liquid interface, the temperature- and composition

  18. Saline groundwater in crystalline bedrock

    International Nuclear Information System (INIS)

    The State-of-art report describes research made on deep saline groundwaters and brines found in crystalline bedrock, mainly in site studies for nuclear waste disposal. The occurrence, definitions and classifications of saline groundwaters are reviewed with a special emphasis on the different theories concerning the origins of saline groundwaters. Studies of the saline groundwaters in Finland and Sweden have been reviewed more thoroughly. Also the mixing of different bodies of groundwaters, observations of the contact of saline groundwaters and permafrost, and the geochemical modelling of saline groundwaters as well as the future trends of research have been discussed. (orig.)

  19. Amorphous and crystalline blast furnace slag

    International Nuclear Information System (INIS)

    Full text: One of the by-products of iron production from a blast furnace is the slag, Generally 250-300 kg of slag is produced per ton of iron. Liquid blast furnace slag can either be cooled quickly by quenching in a granulator or more slowly in air. The air-cooled product is crushed and sized for use as an aggregate in concrete. The granulated slag is ground to form ground granulated slag, which is a cost-effective supplementary cementitious material. Blends of ground granulated slag and Portland cement produce a cementitious paste that is more resistant to chloride penetration than pastes made from the Portland cement alone. In this study neutron diffraction techniques were used to examine samples of air-cooled and granulated slags from Australian Steel Mill Services stock piles at Port Kembla. Sourced from the same blast furnace, the materials should be expected to posses similar elemental chemistry. The mineral compositions would be different due to the rate of cooling each slag was subjected to. Samples, 15 grams in mass, were mounted in a vanadium can and diffraction patterns were measured using the SLAD instrument on the Reactor R-2 at the Studvik Neutron Research Laboratory in Sweden. The diffraction patterns were transformed into radial distribution functions using the reverse Monte Carlo program, MCGR. The granulated slag showed no diffraction peaks while the air cooled slag showed a crystalline product that can be identified by x-ray diffraction. The radial distribution functions showed differences that were consistent with the granulated slag being amorphous and the air-cooled slag crystalline. Both slag samples showed peaks in the radial distribution function at 1.8 Angstroms and 2.8 Angstroms. The greatest anomaly was a feature about 2.5 Angstroms found only in the radial distribution function for the granulated slag. This demonstration showed that there are differences in the short range bonding between the two compounds. We are currently

  20. Crystalline structure in the confined-deconfined mixed phase: Neutron stars as an example

    International Nuclear Information System (INIS)

    We review the differences in first order phase transition of single and multi-component systems, and then discuss the crystalline structure expected to exist in the mixed confined deconfined phase of hadronic matter. The particular context of neutron stars is chosen for illustration. The qualitative results are general and apply for example to the vapor-liquid transition in subsaturated asymmetric nuclear matter

  1. Multiscale Control of Hierarchical Structure in Crystalline Block Copolymer Nanoparticles Using Microfluidics.

    Science.gov (United States)

    Bains, Aman; Cao, Yimeng; Moffitt, Matthew G

    2015-11-01

    Hierarchical semicrystalline block copolymer nanoparticles are produced in a segmented gas-liquid microfluidic reactor with top-down control of multiscale structural features, including nanoparticle morphologies, sizes, and internal crystallinities. Control of multiscale structure on disparate length scales by a single control variable (flow rate) enables tailoring of drug delivery nanoparticle function including release rates. PMID:26305569

  2. New disordering mode for TFSI- anions: the nonequilibrium, plastic crystalline structure of Et4NTFSI.

    Science.gov (United States)

    Henderson, Wesley A; Herstedt, Marie; Young, Victor G; Passerini, Stefano; De Long, Hugh C; Trulove, Paul C

    2006-02-20

    A new TFSI- anion disordering mode has been discovered in a supercooled plastic crystalline phase of Et4NTFSI, which may, in part, account for the low melting points of TFSI- salts with organic cations, thereby forming ionic liquids, and the intriguing properties of LiTFSI for lithium battery applications. PMID:16471945

  3. Birefringence Measurements on Crystalline Silicon

    CERN Document Server

    Krüger, Christoph; Khalaidovski, Alexander; Steinlechner, Jessica; Nawrodt, Ronny; Schnabel, Roman; Lück, Harald

    2015-01-01

    Crystalline silicon has been proposed as a new test mass material in third generation gravitational wave detectors such as the Einstein Telescope (ET). Birefringence can reduce the interferometric contrast and can produce dynamical disturbances in interferometers. In this work we use the method of polarisation-dependent resonance frequency analysis of Fabry-Perot-cavities containing silicon as a birefringent medium. Our measurements show a birefringence of silicon along the (111) axis of the order of $\\Delta\\, n \\approx 10^{-7}$ at a laser wavelength of 1550nm and room temperature. A model is presented that explains the results of different settings of our measurements as a superposition of elastic strains caused by external stresses in the sample and plastic strains possibly generated during the production process. An application of our theory on the proposed ET test mass geometry suggests no critical effect on birefringence due to elastic strains.

  4. Birefringence measurements on crystalline silicon

    Science.gov (United States)

    Krüger, Christoph; Heinert, Daniel; Khalaidovski, Alexander; Steinlechner, Jessica; Nawrodt, Ronny; Schnabel, Roman; Lück, Harald

    2016-01-01

    Crystalline silicon has been proposed as a new test mass material in third generation gravitational wave detectors such as the Einstein telescope (ET). Birefringence can reduce the interferometric contrast and can produce dynamical disturbances in interferometers. In this work we use the method of polarization-dependent resonance-frequency analysis of Fabry-Perot-cavities containing silicon as a birefringent medium. Our measurements show a birefringence of silicon along the (111) axis of the order of {{Δ }} n≈ {10}-7 at a laser wavelength of 1550 nm and room temperature. A model is presented that explains the results of different settings of our measurements as a superposition of elastic strains caused by external stresses in the sample and plastic strains possibly generated during the production process. An application of our theory on the proposed ET test mass geometry suggests no critical effect on birefringence due to elastic strains.

  5. Crystalline color superconductors: A review

    CERN Document Server

    Anglani, Roberto; Ciminale, Marco; Gatto, Raoul; Ippolito, Nicola; Mannarelli, Massimo; Ruggieri, Marco

    2013-01-01

    Non-homogenous superconductors and non-homogenous superfluids appear in a variety of contexts which include quark matter at extreme densities, fermionic systems of cold atoms, type-II cuprates and organic superconductors. In the present review we shall focus on the properties of quark matter at high baryonic density which can exist in the interior of compact stars. The conditions that are realized in this stellar objects tend to disfavor standard symmetric BCS pairing and may be in favor of a non-homogenous color superconducting phase. We discuss in details the properties of non-homogenous color superconductors and in particular of crystalline color superconductors. We also review the possible astrophysical signatures associated with the presence of non-homogenous color superconducting phases within the core of compact stars.

  6. STUDY ON LIQUID CRYSTAL POLYMERS WITH TWO-DIMENSIONAL MESOGENIC UNITS

    Institute of Scientific and Technical Information of China (English)

    ZHANG Chunxiao; LI Zifa; ZHOU Qifeng; ZHOU Hongbing

    1993-01-01

    A series of liquid crystalline polymers with two-dimensional mesogenic units were synthesized by solution polycondensation at low temperature. All the polymers were liquid crystalline. The melting temperature Tm (except that with substituent of methoxy) and the clearing temperature Ti of the polymers change regularly with varying of the length of the alkyl substituent groups.

  7. Self-healing Action of Permeable Crystalline Coating on Pores and Cracks in Cement-based Materials

    Institute of Scientific and Technical Information of China (English)

    WANG Guiming; YU Jianying

    2005-01-01

    The self-healing action of a permeable crystalline coating on the porous mortar was investigated by two times impermeability test. Moreover, the self-healing mechanism of cement-based materials with the permeable crystalline coating was studied by SEM. The results indicate that the permeable crystalline coating not only seals the pores and cracks in mortar during its curing process, but also heals the permeable pathway caused by first impermeability test or cracks produced by freeze-thaw cycles. Therefore, cement-based materials can be improved by the permeable crystalline coating for the self-healing function. SEM images prove that the self-healing function is realized by generating a great quantity of non-soluble dendritic crystalline within the pores and cracks, which prevents the penetration of water and other liquids.

  8. SYNTHESIS AND PROPERTIES OF METAL COMPLEXES OF β-DIKETONE BASED SIDE CHAIN LIQUID CRYSTAL POLYSILOXANE

    Institute of Scientific and Technical Information of China (English)

    WU Fuzhou; ZHANG Rongben; JIANG Yingyan

    1991-01-01

    A new type of metal coordinated liquid crystalline polymers has been synthesized by complexation of metal ions with β-diketone based side chain liquid crystal polysiloxane (DKLCP).The complexation of copper ions with DKLCP greatly increases the phase transition temperature Tk from crystalline state to liquid crystalline state and Tcl from LC to isotropic state and makes the range of phase transition △T(△T= Tcl- Tk ) widened. These complexes are soluble in common organic solvents. However, the incorporation of europium ions into DKLCP molecules gives rise to reduction in liquid crystallinity and crosslinking in some cases. The DKLCP coordinated with suitable amount of Eu ions can show good liquid crystallinity and fluorescent property.

  9. Photoresponsive Liquid Crystals Based on Dihydroazulene

    DEFF Research Database (Denmark)

    Petersen, Anne Ugleholdt

    The main focus of this thesis was a study upon photoresponsive liquid crystalline materials,with a starting point on the photoactive compound dihydroazulene (DHA). It has been shown thatsome DHAs with liquid crystalline properties can be synthesized, having an aliphatic substituent atthe 2-position....... Irradiation of such a DHA in the nematic phase gave partial conversion to avinylheptafulvene (VHF), not showing any changes in the mesophase, though a higher alignmentwas obtained when this sample was irradiated in its liquid crystalline state.Photomicrographs of the DHA under crossed polarizers before...... irradiation, after irradiation and when allowed toclose back to the DHAFor a disubstituted DHAs, with substituents in both the 2- and 7-positions, it was shown thatthese materials were unstable when heated above 100 °C, leading to side reactions, whichcomplicated analysis of the system. When doped into a...

  10. Heavy ion irradiation of crystalline water ice

    CERN Document Server

    Dartois, E; Boduch, P; Brunetto, R; Chabot, M; Domaracka, A; Ding, J J; Kamalou, O; Lv, X Y; Rothard, H; da Silveira, E F; Thomas, J C

    2015-01-01

    Under cosmic irradiation, the interstellar water ice mantles evolve towards a compact amorphous state. Crystalline ice amorphisation was previously monitored mainly in the keV to hundreds of keV ion energies. We experimentally investigate heavy ion irradiation amorphisation of crystalline ice, at high energies closer to true cosmic rays, and explore the water-ice sputtering yield. We irradiated thin crystalline ice films with MeV to GeV swift ion beams, produced at the GANIL accelerator. The ice infrared spectral evolution as a function of fluence is monitored with in-situ infrared spectroscopy (induced amorphisation of the initial crystalline state into a compact amorphous phase). The crystalline ice amorphisation cross-section is measured in the high electronic stopping-power range for different temperatures. At large fluence, the ice sputtering is measured on the infrared spectra, and the fitted sputtering-yield dependence, combined with previous measurements, is quadratic over three decades of electronic ...

  11. Crystallinity and properties of C60 nanotubes improved by annealing and alcohol-soaking

    International Nuclear Information System (INIS)

    Well-uniformed C60 nanotubes were grown at -20 deg. C with irradiation of red light using C60-saturated pyridine solution and isopropyl alcohol by a liquid-liquid interfacial precipitation method without ultrasonic pulverization. We attempted to improve their crystallinity by two post-treatments; thermal annealing and alcohol-soaking. The crystallinity of as-grown and dried C60 nanotubes, which was poor due to the evaporation of solvent molecules from crystals in the drying process, was improved by annealing around 220 deg. C for 5 hours in vacuum. Dramatic improvement of crystallinity of as-grown samples was achieved by soaking into methanol and then drying in air. Raman, infrared and X-ray diffraction results suggest that the methanol-soaked samples exhibit a solvated tetragonal structure. The crystallinity improved by methanol-soaking did not degrade after removal of methanol molecules from samples by thermal annealing. Photo-polymerization of the structurally-improved C60 nanotubes was examined to investigate an effect of crystallinity on the polymerization kinetics.

  12. Macroscopic diffusion models for precipitation in crystalline gallium arsenide

    Energy Technology Data Exchange (ETDEWEB)

    Kimmerle, Sven-Joachim Wolfgang

    2009-09-21

    Based on a thermodynamically consistent model for precipitation in gallium arsenide crystals including surface tension and bulk stresses by Dreyer and Duderstadt, we propose two different mathematical models to describe the size evolution of liquid droplets in a crystalline solid. The first model treats the diffusion-controlled regime of interface motion, while the second model is concerned with the interface-controlled regime of interface motion. Our models take care of conservation of mass and substance. These models generalise the well-known Mullins- Sekerka model for Ostwald ripening. We concentrate on arsenic-rich liquid spherical droplets in a gallium arsenide crystal. Droplets can shrink or grow with time but the centres of droplets remain fixed. The liquid is assumed to be homogeneous in space. Due to different scales for typical distances between droplets and typical radii of liquid droplets we can derive formally so-called mean field models. For a model in the diffusion-controlled regime we prove this limit by homogenisation techniques under plausible assumptions. These mean field models generalise the Lifshitz-Slyozov-Wagner model, which can be derived from the Mullins-Sekerka model rigorously, and is well understood. Mean field models capture the main properties of our system and are well adapted for numerics and further analysis. We determine possible equilibria and discuss their stability. Numerical evidence suggests in which case which one of the two regimes might be appropriate to the experimental situation. (orig.)

  13. Influence of string-like cooperative atomic motion on surface diffusion in the (110) interfacial region of crystalline Ni

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hao, E-mail: hao.zhang@ualberta.ca, E-mail: jack.douglas@nist.gov; Yang, Ying [Department of Chemical and Materials Engineering, University of Alberta, Alberta T6G 2V4 (Canada); Douglas, Jack F., E-mail: hao.zhang@ualberta.ca, E-mail: jack.douglas@nist.gov [Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)

    2015-02-28

    Although we often think about crystalline materials in terms of highly organized arrays of atoms, molecules, or even colloidal particles, many of the important properties of this diverse class of materials relating to their catalytic behavior, thermodynamic stability, and mechanical properties derive from the dynamics and thermodynamics of their interfacial regions, which we find they have a dynamics more like glass-forming (GF) liquids than crystals at elevated temperatures. This is a general problem arising in any attempt to model the properties of naturally occurring crystalline materials since many aspects of the dynamics of glass-forming liquids remain mysterious. We examine the nature of this phenomenon in the “simple” case of the (110) interface of crystalline Ni, based on a standard embedded-atom model potential, and we then quantify the collective dynamics in this interfacial region using newly developed methods for characterizing the cooperative dynamics of glass-forming liquids. As in our former studies of the interfacial dynamics of grain-boundaries and the interfacial dynamics of crystalline Ni nanoparticles (NPs), we find that the interface of bulk crystalline Ni exhibits all the characteristics of glass-forming materials, even at temperatures well below the equilibrium crystal melting temperature, T{sub m}. This perspective offers a new approach to modeling and engineering the properties of crystalline materials.

  14. Influence of string-like cooperative atomic motion on surface diffusion in the (110) interfacial region of crystalline Ni

    International Nuclear Information System (INIS)

    Although we often think about crystalline materials in terms of highly organized arrays of atoms, molecules, or even colloidal particles, many of the important properties of this diverse class of materials relating to their catalytic behavior, thermodynamic stability, and mechanical properties derive from the dynamics and thermodynamics of their interfacial regions, which we find they have a dynamics more like glass-forming (GF) liquids than crystals at elevated temperatures. This is a general problem arising in any attempt to model the properties of naturally occurring crystalline materials since many aspects of the dynamics of glass-forming liquids remain mysterious. We examine the nature of this phenomenon in the “simple” case of the (110) interface of crystalline Ni, based on a standard embedded-atom model potential, and we then quantify the collective dynamics in this interfacial region using newly developed methods for characterizing the cooperative dynamics of glass-forming liquids. As in our former studies of the interfacial dynamics of grain-boundaries and the interfacial dynamics of crystalline Ni nanoparticles (NPs), we find that the interface of bulk crystalline Ni exhibits all the characteristics of glass-forming materials, even at temperatures well below the equilibrium crystal melting temperature, Tm. This perspective offers a new approach to modeling and engineering the properties of crystalline materials

  15. Radiolysis of crystalline nickel oxalates

    Science.gov (United States)

    Basahel, S. N.; Diefallah, El-H. M.; El-Fass, M. M.; Al-Sabban, E. A.

    Radiolysis of crystalline K 2Ni(C 2O 4) 2);6H 2O, K 2Ni(C 2O 4) 2 and Ni(C 2O 4));2H 2O has been investigated. The results showed that in K 2Ni(C 2O 4) 2);6H 2O, the initial G(Ni 3+) has a value of 3.75 and drops to about 1.27 when the dose approaches 1.2 × 10 22 eV g -1. The decrease in G(Ni 3+) with increasing radiation dose is accompanied with an increase in G(Ni 2+). In the irradiated anhydrated complex, the results however show an increase in G(Ni 3+) and a decrease in G(Ni 2+) with increasing radiation dose. The radiolysis of Ni(C 2O 4)·2H 2O showed an increase in G(Ni 3+) with increasing radiation dose. A mechanism has been suggested to explain the observed results.

  16. Crystalline silicotitanate gate review analysis

    International Nuclear Information System (INIS)

    Crystalline silicotitanate (CST) is an ion-exchange method for removing radioactive cesium from tank waste to allow the separation of the waste into high- and low-level fractions. The CST, originally developed Sandia National Laboratories personnel in association with Union Oil Products Corporation, has both a high affinity and selectivity for sorbing cesium-137 from highly alkaline or acidic solutions. For several years now, the U.S. Department of Energy has funded work to investigate applying CST to large-scale removal of cesium-137 from radioactive tank wastes. In January 1997, an expert panel sponsored by the Tanks Focus Area met to review the current state of the technology and to determine whether it was ready for routine use. The review also sought to identify any technical issues that must be resolved or additional CST development that must occur before full implementation by end-users. The CST Gate Review Group concluded that sufficient work has been done to close developmental work on CST and turn the remaining site-specific tasks over to the users. This report documents the review group''s findings, issues, concerns, and recommendations as well as responses from the Tanks Focus Area expert staff to specific pretreatment and immobilization issues

  17. Influence of virtual surfaces on Frank elastic constants in a polymer-stabilized bent-core nematic liquid crystal

    Science.gov (United States)

    Madhuri, P. Lakshmi; Hiremath, Uma S.; Yelamaggad, C. V.; Madhuri, K. Priya; Prasad, S. Krishna

    2016-04-01

    Effect of a polymer network on the threshold voltage of the Fréedericksz transition, Frank elastic constants, switching speed, and the rotational viscosity are investigated in a polymer-stabilized bent-core nematic liquid crystal with different polymer concentrations. These polymer networks form virtual surfaces with a finite anchoring energy. The studies bring out several differences in comparison to similar studies with a calamitic liquid crystal as the nematic host. For example, on varying the polymer content the threshold voltage decreases initially, but exhibits a drastic increase above a critical concentration. A similar feature—reaching a minimum before rising—is seen for the bend elastic constant, which gets enhanced by an order of magnitude for a polymer content of 2.5 wt %. In contrast, the splay elastic constant has a monotonic variation although the overall enhancement is comparable to that of the bend elastic constant. The behavior changing at a critical concentration is also seen for the switching time and the associated rotational viscosity. The presence of the polymer also induces a shape change in the thermal dependence of the bend elastic constant. We explain the features observed here on the basis of images obtained from the optical and atomic force microscopy.

  18. Measurement of crystallinity of thermoplastic natural rubber (TPNR) using x-ray diffraction and thermal methods

    International Nuclear Information System (INIS)

    The measurement of crystallinity of thermoplastic natural rubber (TPNR) of NR:HDPE blends have been made at various compositions of liquid natural rubber (LNR) using x-ray and thermal analysis methods. The results show that the crystallinity of the blends increase significantly with the addition of LNR into the blends. The data indicates a good agreement between the two methods. The tensile properties, stress and strain of the blend improved significantly with addition of LNR. SEM micrographs of the samples also indicates an increase in homogeneity of the blends with addition of LNR. (Author)

  19. Photoinduced magnetic effects in bulk single-crystalline, polycrystalline, and LPE films of Yttrium Iron Garnet

    Science.gov (United States)

    Hisatake, K.; Matsubara, I.; Maeda, K.; Fujiwara, T.; Peters, M.; Abe, S.; Kudo, K.; Kainuma, S.; Tamaki, T.; Kino, Y.; de Francisco, C.; Munoz, J. M.; Alejos, O.; Hernandez, P.; Torres, C.; Shinagawa, K.

    2002-05-01

    The effect of light on magnetic initial permeability (the so-called photomagnetic effect) and photoinduced disaccommodation were studied in samples of yttrium iron garnet over the temperature range 77-300 K. The samples studied were bulk crystalline, produced by the floating zone method and the flux method, polycrystalline, produced by the usual sintering method, and single-crystalline films, produced by in situ liquid-phase epitaxis. One or both of the studied phenomena were observed in our experimental samples. To explain the experimental results, we suggest there is photoinduced structural distortion around oxygen vacancies due to a photoinduced change of charge imbalance.

  20. Ionic motion in crystalline cryolite.

    Science.gov (United States)

    Foy, Lindsay; Madden, Paul A

    2006-08-10

    The character of the ion dynamics in crystalline cryolite, Na(3)AlF(6), a model double perovskite-structured mineral, has been examined in computer simulations using a polarizable ionic potential obtained by force-fitting to ab initio electronic structure calculations. NMR studies, and conductivity measurements, have indicated a high degree of mobility, in both Na(+) ion diffusion and reorientation of the AlF(6) octahedral units. The simulations reproduce the low-temperature (tilted) crystal structure and the existence of a transition to a cubic structure at elevated temperatures, in agreement with diffraction measurements, though the calculated transition temperature is too low. The reorientational dynamics of the AlF(6) octahedra is shown to consist of a hopping motion between the various tilted positions of the low-temperature form, even above the transition temperature. The rate of reorientation estimated by extrapolation to the temperature régime of the NMR measurements is consistent with the experimental data. In addition, we report a novel cooperative "tilt-swapping" motion of the differently tilted sublattices, just below the transition temperature. The perfect crystals show no Na(+) diffusion, in apparent disagreement with observation. We argue, following previous analyses of the cryolite phase diagram, that the diffusion observed in the experimental studies is a consequence of defects that are intrinsic to the thermodynamically stable form of cryolite. By introducing defects into the simulation cell, we obtain diffusion rates that are consistent with the NMR and conductivity measurements. Finally, we demonstrate a link between diffusion of the Na(+) ions and the reorientation of AlF(6) units, though the correlation between the two is not very strong. PMID:16884249

  1. Hydraulic testing in crystalline rock

    International Nuclear Information System (INIS)

    Swedish Geolocical Company (SGAB) conducted and carried out single-hole hydraulic testing in borehole Fi 6 in the Finnsjoen area of central Sweden. The purpose was to make a comprehensive evaluation of different methods applicable in crystalline rocks and to recommend methods for use in current and scheduled investigations in a range of low hydraulic conductivity rocks. A total of eight different methods of testing were compared using the same equipment. This equipment was thoroughly tested as regards the elasticity of the packers and change in volume of the test section. The use of a hydraulically operated down-hole valve enabled all the tests to be conducted. Twelve different 3-m long sections were tested. The hydraulic conductivity calculated ranged from about 5x10-14 m/s to 1x10-6 m/s. The methods used were water injection under constant head and then at a constant rate-of-flow, each of which was followed by a pressure fall-off period. Water loss, pressure pulse, slug and drill stem tests were also performed. Interpretation was carried out using standard transient evaluation methods for flow in porous media. The methods used showed themselves to be best suited to specific conductivity ranges. Among the less time-consuming methods, water loss, slug and drill stem tests usually gave somewhat higher hydraulic conductivity values but still comparable to those obtained using the more time-consuming tests. These latter tests, however, provided supplementary information on hydraulic and physical properties and flow conditions, together with hydraulic conductivity values representing a larger volume of rock. (orig./HP)

  2. Mechanical dispersion in fractured crystalline rock systems

    International Nuclear Information System (INIS)

    This report compiles and evaluates the hydrogeologic parameters describing the flow of groundwater and transport of solutes in fractured crystalline rocks. This report describes the processes of mechanical dispersion in fractured crystalline rocks, and compiles and evaluates the dispersion parameters determined from both laboratory and field tracer experiments. The compiled data show that extrapolation of the reliable test results performed over intermediate scales (10's of m and 10's to 100's of hours) to larger spatial and temporal scales required for performance assessment of a nuclear waste repository in crystalline rock is not justified. The reliable measures of longitudinal dispersivity of fractured crystalline rock are found to range between 0.4 and 7.8 m

  3. The amazing properties of crystalline color superconductors

    International Nuclear Information System (INIS)

    This paper is a brief journey into the amazing realm of crystalline color superconductors. Starting from a qualitative description of superfluids, superconductors and supersolids, we show how inhomogeneous phases may arise when the system is under stress. These basic concepts are then extended to quark matter, in which a richer variety of phases can be realized. The most interesting properties of the crystalline color superconductors are presented. This brief journey ends with a discussion of crystalline color superconductors in compact stars and related astrophysical observables. We aim at providing a pedagogical introduction for nonexpert in the field to a few interesting properties of crystalline color superconductors, without discussing the methods and the technicalities. Thus, the results are presented without a proof. However, we try to give a qualitatively clear description of the main concepts, using standard quantum field theory and analogies with condensed matter systems.

  4. Electrochemical synthesis of highly crystalline copper nanowires

    International Nuclear Information System (INIS)

    Copper nanowires were fabricated within the pores of anodic alumina template (AAT) by template synthesis method at pH = 2.9. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to investigate the structure, morphology and composition of fabricated nanowires. These characterizations revealed that the deposited copper nanowires were highly crystalline in nature, dense and uniform. The crystalline copper nanowires are promising in application of future nanoelectronic devices and circuits

  5. In vivo human crystalline lens topography

    OpenAIRE

    Sergio Ortiz; Pablo P\\xe9rez-Merino; Enrique Gambra; Alberto de Castro; Susana de Marcos

    2012-01-01

    Custom high-resolution high-speed anterior segment spectral domain optical coherence tomography (OCT) was used to characterize three-dimensionally (3-D) the human crystalline lens in vivo. The system was provided with custom algorithms for denoising and segmentation of the images, as well as for fan (scanning) and optical (refraction) distortion correction, to provide fully quantitative images of the anterior and posterior crystalline lens surfaces. The method was tested on an artificial eye ...

  6. Electrochemical synthesis of highly crystalline copper nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Amandeep [Department of Electronics and Communication Engineering, Punjabi University, Patiala 147 002, Punjab (India); Gupta, Tanish; Kumar, Akshay [Department of Nanotechnology, SGGSW University, Fatehgarh Sahib 140406, Punjab (India); Kumar, Sanjeev [Department of Applied Sciences, PEC University of Technology, Chandigarh 160012 (India); Singh, Karamjeet [Department of Physics, Punjabi University, Patiala 147002, Punjab (India); Thakur, Anup, E-mail: dranupthakur@gmail.com [Advanced Materials Research Lab, Department of Basic and Applied Sciences, Punjabi University, Patiala 147 002, Punjab (India)

    2015-05-15

    Copper nanowires were fabricated within the pores of anodic alumina template (AAT) by template synthesis method at pH = 2.9. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to investigate the structure, morphology and composition of fabricated nanowires. These characterizations revealed that the deposited copper nanowires were highly crystalline in nature, dense and uniform. The crystalline copper nanowires are promising in application of future nanoelectronic devices and circuits.

  7. Exact Topological Twistons in Crystalline Polyethylene

    OpenAIRE

    Ventura, E.; Simas, A. M.; D. Bazeia

    2000-01-01

    We investigate the presence of topological twistons in crystalline polyethylene. We describe crystalline polyethylene with a model that couples the torsional and longitudinal degrees of freedom of the polymeric chain by means of a system of two real scalar fields. This model supports topological twistons, which are described by exact and stable topological solutions that appear when the interaction between torsional and longitudinal fields is polynomial, containing up to the sixth power in th...

  8. STM, SECPM, AFM and Electrochemistry on Single Crystalline Surfaces

    Directory of Open Access Journals (Sweden)

    Ulrich Stimming

    2010-08-01

    Full Text Available Scanning probe microscopy (SPM techniques have had a great impact on research fields of surface science and nanotechnology during the last decades. They are used to investigate surfaces with scanning ranges between several 100 mm down to atomic resolution. Depending on experimental conditions, and the interaction forces between probe and sample, different SPM techniques allow mapping of different surface properties. In this work, scanning tunneling microscopy (STM in air and under electrochemical conditions (EC-STM, atomic force microscopy (AFM in air and scanning electrochemical potential microscopy (SECPM under electrochemical conditions, were used to study different single crystalline surfaces in electrochemistry. Especially SECPM offers potentially new insights into the solid-liquid interface by providing the possibility to image the potential distribution of the surface, with a resolution that is comparable to STM. In electrocatalysis, nanostructured catalysts supported on different electrode materials often show behavior different from their bulk electrodes. This was experimentally and theoretically shown for several combinations and recently on Pt on Au(111 towards fuel cell relevant reactions. For these investigations single crystals often provide accurate and well defined reference and support systems. We will show heteroepitaxially grown Ru, Ir and Rh single crystalline surface films and bulk Au single crystals with different orientations under electrochemical conditions. Image studies from all three different SPM methods will be presented and compared to electrochemical data obtained by cyclic voltammetry in acidic media. The quality of the single crystalline supports will be verified by the SPM images and the cyclic voltammograms. Furthermore, an outlook will be presented on how such supports can be used in electrocatalytic studies.

  9. Stability and cytotoxicity of crystallin amyloid nanofibrils

    Science.gov (United States)

    Kaur, Manmeet; Healy, Jackie; Vasudevamurthy, Madhusudan; Lassé, Moritz; Puskar, Ljiljana; Tobin, Mark J.; Valery, Celine; Gerrard, Juliet A.; Sasso, Luigi

    2014-10-01

    Previous work has identified crystallin proteins extracted from fish eye lenses as a cheap and readily available source for the self-assembly of amyloid nanofibrils. However, before exploring potential applications, the biophysical aspects and safety of this bionanomaterial need to be assessed so as to ensure that it can be effectively and safely used. In this study, crude crystallin amyloid fibrils are shown to be stable across a wide pH range, in a number of industrially relevant solvents, at both low and high temperatures, and in the presence of proteases. Crystallin nanofibrils were compared to well characterised insulin and whey protein fibrils using Thioflavin T assays and TEM imaging. Cell cytotoxicity assays suggest no adverse impact of both mature and fragmented crystallin fibrils on cell viability of Hec-1a endometrial cells. An IR microspectroscopy study supports long-term structural integrity of crystallin nanofibrils.Previous work has identified crystallin proteins extracted from fish eye lenses as a cheap and readily available source for the self-assembly of amyloid nanofibrils. However, before exploring potential applications, the biophysical aspects and safety of this bionanomaterial need to be assessed so as to ensure that it can be effectively and safely used. In this study, crude crystallin amyloid fibrils are shown to be stable across a wide pH range, in a number of industrially relevant solvents, at both low and high temperatures, and in the presence of proteases. Crystallin nanofibrils were compared to well characterised insulin and whey protein fibrils using Thioflavin T assays and TEM imaging. Cell cytotoxicity assays suggest no adverse impact of both mature and fragmented crystallin fibrils on cell viability of Hec-1a endometrial cells. An IR microspectroscopy study supports long-term structural integrity of crystallin nanofibrils. Electronic supplementary information (ESI) available: ThT fluorescence graphs of buffers and solvents used for

  10. Quantum creep in a highly crystalline two-dimensional superconductor

    Science.gov (United States)

    Saito, Yu; Kasahara, Yuichi; Ye, Jianting; Iwasa, Yoshihiro; Nojima, Tsutomu

    Conventional studies on quantum phase transitions, especially on superconductor-insulator or superconductor-metal-insulator transitions have been performed in deposited metallic thin films such as Bismuth or MoGe. Although the techniques of thin films deposition have been considerably improved, unintentional disorder such as impurities and deficiencies, generating the pinning centers, seems to still exist in such systems. The mechanical exfoliated highly crystalline two-dimensional material can be a good candidate to realize a less-disordered 2D superconductor with extremely weak pinning, combined with transfer method or ionic-liquid gating. We report on the quantum metal, namely, magnetic-field-induced metallic state observed in an ion-gated two-dimensional superconductor based on an ultra-highly crystalline layered band insulator, ZrNCl. We found that the superconducting state is extremely fragile against external magnetic fields; that is, zero resistance state immediately disappears, once an external magnetic field switches on. This is because the present system is relatively clean and the pinning potential is extremely weak, which cause quantum tunneling and flux flow of vortices, resulting in metallic ground state.

  11. Waste separation and pretreatment using crystalline silicotitanate ion exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Tadros, M.E.; Miller, J.E. [Sandia National Lab., Albuquerque, NM (United States); Anthony, R.G. [Texas A& M Univ., College Station, TX (United States)

    1997-10-01

    A new class of inorganic ion exchangers called crystalline silicotitanates (CSTs) has been developed jointly by Sandia National Laboratories and Texas A&M University to selectively remove Cs and other radionuclides from a wide spectrum of radioactive defense wastes. The CST exhibits high selectivity and affinity for Cs and Sr under a wide range of conditions. Tests show it can remove part-per-million concentrations of Cs{sup +} from highly alkaline, high-sodium simulated radioactive waste solutions modeled after those at Hanford, Oak Ridge, and Savannah River. The materials exhibit ion exchange properties based on ionic size selectivity. Specifically, crystalline lattice spacing is controlled to be highly selective for Cs ions even in waste streams containing very high (5 to 10 M) concentrations of sodium. The CST technology is being demonstrated with actual waste at several DOE facilities. The use of inorganic ion exchangers. The inorganics are more resistant to chemical, thermal, and radiation degradation. Their high selectivities result in more efficient operations offering the possibility of a simple single-pass operation. In contrast, regenerable organic ion exchangers require additional processing equipment to handle the regeneration liquids and the eluant with the dissolved Cs.

  12. Characterization of the scintillation anisotropy in crystalline stilbene scintillator detectors

    CERN Document Server

    Schuster, Patricia

    2016-01-01

    This paper reports a series of measurements that characterize the directional dependence of the scintillation response of crystalline melt-grown and solution-grown stilbene to incident DT and DD neutrons. These measurements give the amplitude and pulse shape dependence on the proton recoil direction over one hemisphere of the crystal, confirming and extending previous results in the literature for melt-grown stilbene and providing the first measurements for solution-grown stilbene. In similar measurements of liquid and plastic detectors, no directional dependence was observed, confirming the hypothesis that the anisotropy in stilbene and other organic crystal scintillators is a result of internal effects due to the molecular or crystal structure and not an external effect on the measurement system.

  13. Fractal Liquids

    OpenAIRE

    Heinen, Marco; Schnyder, Simon K.; Brady, John F.; Löwen, Hartmut

    2015-01-01

    We introduce fractal liquids by generalizing classical liquids of integer dimensions d=1,2,3 to a fractal dimension df. The particles composing the liquid are fractal objects and their configuration space is also fractal, with the same non-integer dimension. Realizations of our generic model system include microphase separated binary liquids in porous media, and highly branched liquid droplets confined to a fractal polymer backbone in a gel. Here we study the thermodynamics and pair correlati...

  14. Self-assembly of light-harvesting crystalline nanosheets in aqueous media.

    Science.gov (United States)

    Shahar, Chen; Baram, Jonathan; Tidhar, Yaron; Weissman, Haim; Cohen, Sidney R; Pinkas, Iddo; Rybtchinski, Boris

    2013-04-23

    A methodology leading to facile self-assembly of crystalline aromatic arrays in dilute aqueous solutions would enable efficient fabrication and processing of organic photonic and electronic materials in water. In particular, soluble 2D crystalline nanosheets may mimic the properties of photoactive thin films and self-assembled monolayers, covering large areas with ordered nanometer-thick material. We designed such solution-phase arrays using hierarchical self-assembly of amphiphilic perylene diimides in aqueous media. The assemblies were characterized by cryogenic transmission electron microscopy (cryo-TEM), revealing crystalline order and 2D morphology (confirmed by AFM studies). The order and morphology are preserved upon drying as evidenced by TEM and AFM. The 2D crystalline-like structures exhibit broadening and red-shifted absorption bands in UV-vis spectra, typical for PDI crystals and liquid crystals. Photophysical studies including femtosecond transient absorption spectroscopy reveal that two of the assemblies are superior light-harvesters due to excellent solar spectrum coverage and fast exciton transfer, in one case showing exciton diffusion comparable to solid-state crystalline systems based on perylene tetracarboxylic dianhidride (PTCDA). PMID:23521176

  15. Novel UV-emitting single crystalline film phosphors grown by LPE method

    Czech Academy of Sciences Publication Activity Database

    Zorenko, Y.; Gorbenko, V.; Savchyn, V.; Voznyak, T.; Nikl, Martin; Mareš, Jiří A.; Winnacker, A.

    2010-01-01

    Roč. 45, 3-6 (2010), 444-448. ISSN 1350-4487 R&D Projects: GA ČR GA202/08/0893 Institutional research plan: CEZ:AV0Z10100521 Keywords : UV luminescence * single crystalline film * liquid phase epitaxy * garnets and perovskites * Ce 3+ * Pr 3+ * La 3+ * Sc 3+ * Bi 3+ dopants Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.019, year: 2010

  16. Confocal Raman studies in determining crystalline nature of PECVD grown Si nanowires

    International Nuclear Information System (INIS)

    Silicon nanowires of diameter ∼200 nm and length of 2-4 µm are grown in the plasma enhanced chemical vapour deposition technique using nanoclustered Au catalyst assisted vapour-liquid-solid process. The crystallinity in the as-grown and annealed samples is studied using confocal Raman spectroscopic studies. Amorphous phase is formed in the as-grown samples. Structural studies using high resolution transmission electron microscopy confirm the polycrystalline nature in the annealed sample

  17. Confocal Raman studies in determining crystalline nature of PECVD grown Si nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Nafis; Bhargav, P. Balaji; Ramasamy, P. [SSN Research Centre, Kalavakkam-603110, Tamilnadu (India); Department of Physics, SSN College of Engineering, Kalavakkam-603110, Tamilnadu (India); Sivadasan, A. K.; Tyagi, A. K.; Dhara, S., E-mail: dhara@igcar.gov.in [Surface and Nanoscience Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Amirthapandian, S.; Panigrahi, B. K. [Materials Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Bhattacharya, S. [SSN Research Centre, Kalavakkam-603110, Tamilnadu (India)

    2015-06-24

    Silicon nanowires of diameter ∼200 nm and length of 2-4 µm are grown in the plasma enhanced chemical vapour deposition technique using nanoclustered Au catalyst assisted vapour-liquid-solid process. The crystallinity in the as-grown and annealed samples is studied using confocal Raman spectroscopic studies. Amorphous phase is formed in the as-grown samples. Structural studies using high resolution transmission electron microscopy confirm the polycrystalline nature in the annealed sample.

  18. Efficient aziridine synthesis in metastable crystalline phases by photoinduced denitrogenation of crystalline triazolines.

    Science.gov (United States)

    de Loera, Denisse; Garcia-Garibay, Miguel A

    2012-08-01

    The solid-state photodenitrogenation of crystalline triazolines proceeds with high efficiency to form the corresponding aziridines in high chemical yields upon selection of the proper irradiation wavelength. It was shown that the solid-to-solid reactions occur by formation of the product in metastable crystalline phases. PMID:22794188

  19. Role of Molecular Structure on X-ray Diffraction in Thermotropic Uniaxial and Biaxial Nematic Liquid Crystal Phases

    Energy Technology Data Exchange (ETDEWEB)

    Acharya, Bharat R.; Kang, Shin-Woong; Prasad, Veena; Kumar, Satyendra; (Kent); (Platypus)

    2009-08-27

    X-ray diffraction is one of the most definitive methods to determine the structure of condensed matter phases, and it has been applied to unequivocally infer the structures of conventional calamitic and lyotropic liquid crystals. With the advent of bent-core and tetrapodic mesogens and the discovery of the biaxial nematic phase in them, the experimental results require more careful interpretation and analysis. Here, we present ab-initio calculations of X-ray diffraction patterns in the isotropic, uniaxial nematic, and biaxial nematic phases of bent-core mesogens. A simple Meier-Saupe-like molecular distribution function is employed to describe both aligned and unaligned mesophases. The distribution function is decomposed into two, polar and azimuthal, distribution functions to calculate the effect of the evolution of uniaxial and biaxial nematic orientational order. The calculations provide satisfactory semiquantitative interpretations of experimental results. The calculations presented here should provide a pathway to more refined and quantitative analysis of X-ray diffraction data from the biaxial nematic phase.

  20. Role of Molecular Structure on X-ray Diffraction in Uniaxial and Biaxial Phases of Thermotropic Liquid Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Acharya, Bharat R.; Kang, Shin-Woong; Prasad, Veena; Kumar, Satyendra; (Kent); (CLCR); (Platypus)

    2009-04-29

    X-ray diffraction is one of the most definitive methods to determine the structure of condensed matter phases, and it has been applied to unequivocally infer the structures of conventional calamitic and lyotropic liquid crystals. With the advent of bent-core and tetrapodic mesogens and the discovery of the biaxial nematic phase in them, the experimental results require more careful interpretation and analysis. Here, we present ab-initio calculations of X-ray diffraction patterns in the isotropic, uniaxial nematic, and biaxial nematic phases of bent-core mesogens. A simple Meier-Saupe-like molecular distribution function is employed to describe both aligned and unaligned mesophases. The distribution function is decomposed into two, polar and azimuthal, distribution functions to calculate the effect of the evolution of uniaxial and biaxial nematic orientational order. The calculations provide satisfactory semiquantitative interpretations of experimental results. The calculations presented here should provide a pathway to more refined and quantitative analysis of X-ray diffraction data from the biaxial nematic phase.

  1. Irreducible tensor operators and crystalline potentials

    International Nuclear Information System (INIS)

    It is often accepted that the effects of its neighbourhood on the quantum state of an ion A may be obtained by the model of the crystalline effective field approximation. Within this assumption Stevens has developed a method which provides equivalent operators that facilitate the calculation of the matrix elements of the crystalline field in a given multiplicity. This method has been extended here. We demonstrate that in the expansion of the crystalline field in powers of the electrons coordinates of the ion A - for electrons of the same sub-shell of A - only even terms can contribute. Equivalent operators and matrix elements, in a given multiplicity, are given for these development terms - up to order 6 - and for potential invariant by the operations of one of the thirty-two point-groups. (author)

  2. Structural changes in bunched crystalline ion beams

    International Nuclear Information System (INIS)

    Measurements of the spatial distribution of bunched crystalline ion beams in the radio frequency quadrupole storage ring PALLAS are presented for different ratios of the longitudinal and the transverse confinement strengths. The length of highly elongated crystalline ion bunches and its dependence on the bunching voltage is compared to predictions for a one-dimensional ion string and three-dimensional space-charge-dominated beams. The length is found to be considerably shorter than that predicted by the models. Furthermore, the scaling of the length with the bunching voltage is shown to differ from the expected inverse cube root scaling. These differences can partially be attributed to the formation of a mixed crystalline structure. Additionally, a concise mapping of the structural transition from a string to a zig-zag configuration as a function of the ratio of the confinement strengths is presented, which in a similar way deviates from the predictions

  3. Structural changes in bunched crystalline ion beams

    CERN Document Server

    Bussmann, M; Schätz, T; Habs, D

    2003-01-01

    Measurements of the spatial distribution of bunched crystalline ion beams in the radio frequency quadrupole storage ring PALLAS are presented for different ratios of the longitudinal and the transverse confinement strengths. The length of highly elongated crystalline ion bunches and its dependence on the bunching voltage is compared to predictions for a one-dimensional ion string and three-dimensional space-charge-dominated beams. The length is found to be considerably shorter than that predicted by the models. Furthermore, the scaling of the length with the bunching voltage is shown to differ from the expected inverse cube root scaling. These differences can partially be attributed to the formation of a mixed crystalline structure. Additionally, a concise mapping of the structural transition from a string to a zig-zag configuration as a function of the ratio of the confinement strengths is presented, which in a similar way deviates from the predictions.

  4. Observation of atomic collisions in crystalline solids

    CERN Document Server

    Nelson, R S; Gevers, R

    2013-01-01

    The Observation of Atomic Collisions in Crystalline Solids presents a critical account of the more important experiments which have provided the basis for a better understanding of atomic collision phenomena in crystalline solids. Collisions have been divided into two artificial regimes; primary collisions which deal with the interaction of the incident particles with the solid, and secondary collisions which deal with those events which occur as a result of lattice atoms recoiling from primary encounters. Although the book is intended principally for the experimentalist some simple theoretica

  5. Crystalline Fullerenes. Round Pegs in Square Holes

    OpenAIRE

    Fleming, R. M.; Hessen, B.; Siegrist, T.; Kortan, A.R.; Marsh, P; Tycko, R.; Dabbagh, G.; Haddon, R C

    1992-01-01

    The fullerenes C60 and C70 act as spherical building blocks in crystalline solids to form a variety of crystal structures. In many cases, the icosahedral molecular symmetry of C60 appears to play little role in determining the crystal structure. In this chapter we discuss our results on the crystallography of pure and solvated fullerenes and some general features of fullerenes as building units in crystalline solids. For pure C60 or C70, the face-centered cubic arrangement is preferred. In so...

  6. A Single-Crystalline Mesoporous Quartz Superlattice.

    Science.gov (United States)

    Matsuno, Takamichi; Kuroda, Yoshiyuki; Kitahara, Masaki; Shimojima, Atsushi; Wada, Hiroaki; Kuroda, Kazuyuki

    2016-05-10

    There has been significant interest in the crystallization of nanostructured silica into α-quartz because of its physicochemical properties. We demonstrate a single-crystalline mesoporous quartz superlattice, a silica polymorph with unprecedentedly ordered hierarchical structures on both the several tens of nanometers scale and the atomic one. The mesoporous quartz superlattice consists of periodically arranged α-quartz nanospheres whose crystalline axes are mostly oriented in an assembly. The superlattice is prepared by thermal crystallization of amorphous silica nanospheres constituting a colloidal crystal. We found that the deposition of a strong flux of Li(+) only on the surface of silica nanospheres is effective for crystallization. PMID:27060365

  7. Tensile Deformation of Polyethylenes: Crystallinity Effects

    Science.gov (United States)

    Crist, Buckley; Metaxas, Costas

    2004-03-01

    The crystalline fraction of polyethylene can be reduced by increasing the cooling rate, the molecular weight or the fraction of comonomer. All three methods have been used in this study of tensile deformation which shows that true stress - true strain behavior depends systematically on morphology. The dependence of uniaxial yield stress on crystal thickness is well understood in terms of dislocation nucleation. Post yield flow is dominated by the strain hardening rate that is larger in polyethylenes of lower crystallinity. Noncrystalline polymer evidently reduces the plastic compliance while providing for elastic (reversible) strains. These observations are examined in terms of old and new theories for deformation of semicrystalline polymers.

  8. Electronic processes in non-crystalline materials

    CERN Document Server

    Mott, Nevill Francis

    2012-01-01

    Since the first edition of this highly successful book the field saw many great developments both in experimental and theoretical studies of electrical properties of non-crystalline solids. It became necessary to rewrite nearly the whole book, while the aims of the second edition remained the same: to set out the theoretical concepts, to test them by comparison with experiment for a wide variety of phenomena, and to apply them to non-crystalline materials. Sir Nevill Mott shared the1977 Nobel Prize for Physics, awarded for his research work in this field. The reissue of this book as part of th

  9. Exact Topological Twistons in Crystalline Polyethylene

    CERN Document Server

    Ventura, E; Bazeia, D

    2000-01-01

    We investigate the presence of topological twistons in crystalline polyethylene. We describe crystalline polyethylene with a model that couples the torsional and longitudinal degrees of freedom of the polymeric chain by means of a system of two real scalar fields. This model supports topological twistons, which are described by exact and stable topological solutions that appear when the interaction between torsional and longitudinal fields is polynomial, containing up to the sixth power in the fields. We calculate the energy of the topological twiston, and the result is in very good agreement with the value obtained via molecular simulation.

  10. Liquid crystal nanocomposites produced by mixtures of hydrogen bonded achiral liquid crystals and functionalized carbon nanotubes

    Science.gov (United States)

    Katranchev, B.; Petrov, M.; Keskinova, E.; Naradikian, H.; Rafailov, P. M.; Dettlaff-Weglikowska, U.; Spassov, T.

    2014-12-01

    The liquid crystalline (LC) nature of alkyloxybenzoic acids is preserved after adding of any mesogenic or non-mesogenic compound through hydrogen bonding. However, this noncovalent interaction provokes a sizable effect on the physical properties as, e. g. melting point and mesomorphic states. In the present work we investigate nanocomposites, prepared by mixture of the eighth homologue of p-n-alkyloxybenzoic acids (8OBA) with single-walled carbon nanotubes (SWCNT) with the purpose to modify the optical properties of the liquid crystal. We exercise optical control on the LC system by inserting SWCNT specially functionalized by carboxylic groups. Since the liquid crystalline state combines order and mobility at the molecular (nanoscale) level, molecular modification can lead to different macroscopical nanocomposite symmetry. The thermal properties of the functionalized nanocomposite are confirmed by DSC analyses. The mechanism of the interaction between surface-treated nanoparticles (functionalized nanotubes) and the liquid crystal 8OBA bent- dimer molecules is briefly discussed.

  11. Tailor cutting of crystalline solar cells by laser micro jet

    Science.gov (United States)

    Bruckert, F.; Pilat, E.; Piron, P.; Torres, P.; Carron, B.; Richerzhagen, B.; Pirot, M.; Monna, R.

    2012-03-01

    Coupling a laser into a hair thin water micro jet (Laser Micro Jet, LMJ) for cutting applications offers a wide range of processes that are quite unique. As the laser beam is guided by internal reflections inside of a liquid cylinder, the cuts are naturally straight and do not reflect any divergence as otherwise occurs with an unguided laser beam. Furthermore, having a liquid media at the point of contact ensures a fast removal of heat and eventual debris ensuring clean cuts, which are free of any burrs. Many applications have indeed been developed for a large variety of materials, which are as different as e.g. diamond, silicon, aluminum, ceramic and hard metals. The photovoltaic industry has enjoyed in the last decades tremendous growth rates, which are still projected into the future. We focus here on the segment of Building Integrated PV (BIPV), which requests tailored solutions to actual buildings and not-one-fits-it-all standardized modules. Having the option to tailor cut solar cells opens a new field of BIPV applications. For the first time, finished crystalline solar cells have been LMJ cut into predetermined shapes. First results show that the cut is clean and neat. Preliminary solar performance measurements are positive. This opens a new avenue of tailored made modules instead of having to rely on the one-fits-alloy approach used so far.

  12. Liquid-liquid extraction columns

    International Nuclear Information System (INIS)

    The patent concerns liquid-liquid extraction columns in which solute transfer across the liquid-liquid interface sets up Marangoni instabilities which give rise to interfacial turbulence. The phenomenon has been observed to occur in the solvent extraction of uranium and/or plutonium from an aqueous nitric phase using tributyl phosphate with odourless kerosens. The invention provides a method of quantifying the degree of Marangoni instabilities in a column-type liquid-liquid extraction column, and determining a value for the solute free characteristic velocity parameter. The method also gives a measure of the extent to which the characteristic velocity is modified by the Marangoni instability. (U.K.)

  13. Liquid-liquid extraction columns

    Energy Technology Data Exchange (ETDEWEB)

    Batey, W.; Lonie, S.J.; Thompson, P.J.; Thornton, J.D.

    1987-11-11

    The patent concerns liquid-liquid extraction columns in which solute transfer across the liquid-liquid interface sets up Marangoni instabilities which give rise to interfacial turbulence. The phenomenon has been observed to occur in the solvent extraction of uranium and/or plutonium from an aqueous nitric phase using tributyl phosphate with odourless kerosens. The invention provides a method of quantifying the degree of Marangoni instabilities in a column-type liquid-liquid extraction column, and determining a value for the solute free characteristic velocity parameter. The method also gives a measure of the extent to which the characteristic velocity is modified by the Marangoni instability. (U.K.).

  14. Liquid Ventilation

    OpenAIRE

    Tawfic, Qutaiba A.

    2011-01-01

    Mammals have lungs to breathe air and they have no gills to breath liquids. When the surface tension at the air-liquid interface of the lung increases, as in acute lung injury, scientists started to think about filling the lung with fluid instead of air to reduce the surface tension and facilitate ventilation. Liquid ventilation (LV) is a technique of mechanical ventilation in which the lungs are insufflated with an oxygenated perfluorochemical liquid rather than an oxygen-containing gas mixt...

  15. Electro-osmosis in nematic liquid crystals

    Science.gov (United States)

    Tovkach, O. M.; Calderer, M. Carme; Golovaty, Dmitry; Lavrentovich, Oleg; Walkington, Noel J.

    2016-07-01

    We derive a mathematical model of a nematic electrolyte based on a variational formulation of nematodynamics. We verify the model by comparing its predictions to the results of the experiments on the substrate-controlled liquid-crystal-enabled electrokinetics. In the experiments, a nematic liquid crystal confined to a thin planar cell with surface-patterned anchoring conditions exhibits electro-osmotic flows along the "guiding rails" imposed by the spatially varying director. Extending our previous work, we consider a general setup which incorporates dielectric anisotropy of the liquid-crystalline matrix and the full set of nematic viscosities.

  16. Genetics Home Reference: Bietti crystalline dystrophy

    Science.gov (United States)

    ... Hayakawa M, Kanai A, Shy Chen M, Alan Lewis R, Heckenlively J, Weleber RG, Traboulsi EI, Zhang Q, Xiao X, Kaiser-Kupfer M, Sergeev YV, Hejtmancik JF. Bietti crystalline corneoretinal dystrophy is caused by mutations in the novel gene CYP4V2. Am J Hum Genet. 2004 May;74( ...

  17. Crystalline Fullerenes. Round Pegs in Square Holes

    NARCIS (Netherlands)

    Fleming, R.M.; Hessen, B.; Siegrist, T.; Kortan, A.R.; Marsh, P.; Tycko, R.; Dabbagh, G.; Haddon, R.C.

    1992-01-01

    The fullerenes C60 and C70 act as spherical building blocks in crystalline solids to form a variety of crystal structures. In many cases, the icosahedral molecular symmetry of C60 appears to play little role in determining the crystal structure. In this chapter we discuss our results on the crystall

  18. Quasi-crystalline geometry for architectural structures

    DEFF Research Database (Denmark)

    Wester, Ture; Weinzieri, Barbara

    The quasi-crystal (QC) type of material was discovered in 1983 by Dan Schechtman from Technion, Haifa. This new crystalline structure of material broke totally with the traditional conception of crystals and geometry introducing non-periodic close packing of cells with fivefold symmetry in 3D spa...

  19. Chiral all-organic nitroxide biradical liquid crystals showing remarkably large positive magneto-LC effects.

    Science.gov (United States)

    Suzuki, Katsuaki; Takemoto, Yusa; Takaoka, Shohei; Taguchi, Koji; Uchida, Yoshiaki; Mazhukin, Dmitrii G; Grigor'ev, Igor A; Tamura, Rui

    2016-03-11

    The liquid crystalline chiral nitroxide biradical (S,S,S,S)-3 synthesized has shown much larger 'positive magneto-LC effects' in the chiral nematic (N*) phase than the monoradical (S,S)-1. PMID:26871609

  20. Phase separations in mixtures of a liquid crystal and a nanocolloidal particle

    Science.gov (United States)

    Matsuyama, Akihiko

    2009-11-01

    We present a mean field theory to describe phase separations in mixtures of a liquid crystal and a nanocolloidal particle. By taking into account a nematic, a smectic A ordering of the liquid crystal, and a crystalline ordering of the nanoparticle, we calculate the phase diagrams on the temperature-concentration plane. We predict various phase separations, such as a smectic A-crystal phase separation and a smectic A-isotropic-crystal triple point, etc., depending on the interactions between the liquid crystal and the colloidal surface. Inside binodal curves, we find new unstable and metastable regions, which are important in the phase ordering dynamics. We also find a crystalline ordering of the nanoparticles dispersed in a smectic A phase and a nematic phase. The cooperative phenomena between liquid-crystalline ordering and crystalline ordering induce a variety of phase diagrams.